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Beetles are
insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...
s that form the
order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...
Coleoptera (), in the superorder
Endopterygota Endopterygota (from Ancient Greek ''endon'' 'inner' + ''pterón'' 'wing' + New Latin ''-ota'' 'having'), also known as Holometabola, is a superorder of insects within the infraclass Neoptera that go through distinctive larval, pupal, and adult s ...
. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 described species, is the largest of all orders, constituting almost 40% of described insects and 25% of all known animal life-forms; new species are discovered frequently, with estimates suggesting that there are between 0.9 and 2.1 million total species. Found in almost every habitat except the sea and the
polar region The polar regions, also called the frigid geographical zone, zones or polar zones, of Earth are the regions of the planet that surround its geographical poles (the North Pole, North and South Poles), lying within the polar circles. These high l ...
s, they interact with their
ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...
s in several ways: beetles often feed on plants and
fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
, break down animal and plant debris, and eat other
invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...
s. Some species are serious agricultural pests, such as the Colorado potato beetle, while others such as
Coccinellidae Coccinellidae () is a widespread family of small beetles ranging in size from . They are commonly known as ladybugs in North America and ladybirds in Great Britain. Some entomologists prefer the names ladybird beetles or lady beetles as they ...
(ladybirds or ladybugs) eat aphids,
scale insect Scale insects are small insects of the order Hemiptera, suborder Sternorrhyncha. Of dramatically variable appearance and extreme sexual dimorphism, they comprise the infraorder Coccomorpha which is considered a more convenient grouping than the ...
s,
thrips Thrips ( order Thysanoptera) are minute (mostly long or less), slender insects with fringed wings and unique asymmetrical mouthparts. Different thrips species feed mostly on plants by puncturing and sucking up the contents, although a few are ...
, and other plant-sucking insects that damage crops. Beetles typically have a particularly hard
exoskeleton An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton (endoskeleton) in for example, a human. In usage, some of the ...
including the elytra, though some such as the rove beetles have very short elytra while
blister beetle Blister beetles are beetles of the family Meloidae, so called for their defensive secretion of a blistering agent, cantharidin. About 7,500 species are known worldwide. Many are conspicuous and some are aposematically colored, announcing their ...
s have softer elytra. The general
anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its ...
of a beetle is quite uniform and typical of insects, although there are several examples of novelty, such as adaptations in water beetles which trap air bubbles under the elytra for use while diving. Beetles are endopterygotes, which means that they undergo complete
metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some inse ...
, with a series of conspicuous and relatively abrupt changes in body structure between hatching and becoming adult after a relatively immobile
pupa A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...
l stage. Some, such as
stag beetle Stag beetles are a family of about 1,200 species of beetles in the family Lucanidae, currently classified in four subfamilies.Smith, A.B.T. (2006). A review of the family-group names for the superfamily Scarabaeoidea (Coleoptera) with corrections ...
s, have a marked
sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...
, the males possessing enormously enlarged mandibles which they use to fight other males. Many beetles are aposematic, with bright colors and patterns warning of their toxicity, while others are harmless
Batesian mimics Batesian mimicry is a form of mimicry where a harmless species has evolved to imitate the warning signals of a harmful species directed at a predator of them both. It is named after the English naturalist Henry Walter Bates, after his work on Bu ...
of such insects. Many beetles, including those that live in sandy places, have effective
camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the ...
. Beetles are prominent in human culture, from the sacred scarabs of ancient Egypt to beetlewing art and use as pets or fighting insects for entertainment and gambling. Many beetle groups are brightly and attractively colored making them objects of collection and decorative displays. Over 300 species are used as food, mostly as
larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...
e; species widely consumed include mealworms and rhinoceros beetle larvae. However, the major impact of beetles on human life is as agricultural, forestry, and horticultural
pests PESTS was an anonymous American activist group formed in 1986 to critique racism, tokenism, and exclusion in the art world. PESTS produced newsletters, posters, and other print material highlighting examples of discrimination in gallery represent ...
. Serious pests include the boll weevil of cotton, the Colorado potato beetle, the coconut hispine beetle, and the mountain pine beetle. Most beetles, however, do not cause economic damage and many, such as the
lady beetle Coccinellidae () is a widespread family of small beetles ranging in size from . They are commonly known as ladybugs in North America and ladybirds in Great Britain. Some entomologists prefer the names ladybird beetles or lady beetles as they ...
s and
dung beetle Dung beetles are beetles that feed on feces. Some species of dung beetles can bury dung 250 times their own mass in one night. Many dung beetles, known as ''rollers'', roll dung into round balls, which are used as a food source or breeding cha ...
s are beneficial by helping to control insect pests.


Etymology

The name of the taxonomic order, Coleoptera, comes from the Greek ''koleopteros'' (κολεόπτερος), given to the group by
Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of phil ...
for their elytra, hardened shield-like forewings, from ''koleos'', sheath, and ''pteron'', wing. The English name beetle comes from the
Old English Old English (, ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the early Middle Ages. It was brought to Great Britain by Anglo-Saxon settlement of Britain, Anglo ...
word ''bitela'', little biter, related to ''bītan'' (to bite), leading to
Middle English Middle English (abbreviated to ME) is a form of the English language that was spoken after the Norman conquest of 1066, until the late 15th century. The English language underwent distinct variations and developments following the Old English p ...
''betylle''. Another Old English name for beetle is ''ċeafor'', chafer, used in names such as cockchafer, from the Proto-Germanic *''kebrô'' ("beetle"; compare German ''Käfer'', Dutch ''kever'').


Distribution and diversity

Beetles are by far the largest order of insects: the roughly 400,000 species make up about 40% of all insect species so far described, and about 25% of all animals. McHugh (2009) A 2015 study provided four independent estimates of the total number of beetle species, giving a mean estimate of some 1.5 million with a "surprisingly narrow range" spanning all four estimates from a minimum of 0.9 to a maximum of 2.1 million beetle species. The four estimates made use of host-specificity relationships (1.5 to 1.9 million), ratios with other taxa (0.9 to 1.2 million), plant:beetle ratios (1.2 to 1.3), and extrapolations based on body size by year of description (1.7 to 2.1 million). Beetles are found in nearly all habitats, including freshwater and coastal habitats, wherever vegetative foliage is found, from trees and their bark to flowers, leaves, and underground near roots - even inside plants in galls, in every plant tissue, including dead or decaying ones. Tropical forest canopies have a large and diverse fauna of beetles, including Carabidae, Chrysomelidae, and Scarabaeidae. The heaviest beetle, indeed the heaviest insect stage, is the
larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...
of the
goliath beetle The Goliath beetles (named after the biblical giant Goliath) are any of the five species in the genus ''Goliathus''. Goliath beetles are among the largest insects on Earth, if measured in terms of size, bulk and weight.Karl Meye/ref> They are me ...
, ''Goliathus goliatus'', which can attain a mass of at least and a length of . Adult male goliath beetles are the heaviest beetle in its adult stage, weighing and measuring up to . Adult
elephant beetle The elephant beetle (''Megasoma elephas'') is a member of the family Scarabaeidae and the subfamily Dynastinae. They are Neotropical rhinoceros beetles. Appearance Elephant beetles are black in color and covered with a coat of fine microscopic ...
s, ''
Megasoma elephas The elephant beetle (''Megasoma elephas'') is a member of the family Scarabaeidae and the subfamily Dynastinae. They are Neotropical rhinoceros beetles. Appearance Elephant beetles are black in color and covered with a coat of fine microscopic ...
'' and ''
Megasoma actaeon Actaeon beetle (''Megasoma actaeon'') is a rhinoceros beetle of the family Scarabaeidae. Etymology The species name ''actaeon'' derives from the name Actaeon of a famous Theban hero, son of the priestly herdsman Aristaeus and Autonoe in Boeot ...
'' often reach and . The longest beetle is the
Hercules beetle The Hercules beetle (''Dynastes hercules'') is a species of rhinoceros beetle native to the rainforests of Central America, South America, and the Lesser Antilles. It is the longest extant species of beetle in the world, and is also one of the ...
''Dynastes hercules'', with a maximum overall length of at least 16.7 cm (6.6 in) including the very long pronotal horn. The smallest recorded beetle and the smallest free-living insect (), is the
featherwing beetle Ptiliidae is a family of very tiny beetles with a cosmopolitan distribution. This family contains the smallest of all beetles, with a length when fully grown of . The weight is approximately 0.4 milligrams. They are colloquially called feat ...
''
Scydosella musawasensis ''Scydosella'' is a genus of beetles that consists of only one species ''Scydosella musawasensis''. The species is regarded as the smallest free-living insect, as well as the smallest beetle. They are among featherwing beetle, named because of ...
'' which may measure as little as 325 
μm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...
in length. File:Titanus giganteus MHNT dos.jpg,
Titan beetle The titan beetle (''Titanus giganteus'') is a Neotropical longhorn beetle, the sole species in the genus ''Titanus'', and one of the largest known beetles. Description The titan beetle is one of the largest beetles, with the largest reliable mea ...
, ''Titanus giganteus'', a tropical longhorn, is one of the largest and heaviest insects in the world. File:Scydosella musawasensis.jpg, ''
Scydosella musawasensis ''Scydosella'' is a genus of beetles that consists of only one species ''Scydosella musawasensis''. The species is regarded as the smallest free-living insect, as well as the smallest beetle. They are among featherwing beetle, named because of ...
'', the smallest known beetle: scale bar (right) is 50 μm. File:Dynastes hercules ecuatorianus MHNT.jpg,
Hercules beetle The Hercules beetle (''Dynastes hercules'') is a species of rhinoceros beetle native to the rainforests of Central America, South America, and the Lesser Antilles. It is the longest extant species of beetle in the world, and is also one of the ...
, ''Dynastes hercules ecuatorianus'', the longest of all beetles File:Protaetia-cuprea-ignicollis-IZE-257.jpg, iridescent '' Protaetia cuprea'' feeding on thistle


Evolution


Late Paleozoic and Triassic

The oldest known beetle is ''
Coleopsis ''Coleopsis archaica'' is an extinct species of stem-group beetle. It is the only member of the genus ''Coleopsis'' and family Coleopsidae. It is known from a single specimen from the Early Permian (Asselian) of western Germany, estimated to be a ...
'', from the earliest Permian ( Asselian) of Germany, around 295 million years ago. Early beetles from the Permian, which are collectively grouped into the " Protocoleoptera" are thought to have been
xylophagous Xylophagy is a term used in ecology to describe the habits of an herbivorous animal whose diet consists primarily (often solely) of wood. The word derives from Greek ''ξυλοφάγος'' (''xulophagos'') "eating wood", from ''ξύλον'' (') ...
(wood eating) and wood boring. Fossils from this time have been found in Siberia and Europe, for instance in the red slate fossil beds of Niedermoschel near Mainz, Germany. Further fossils have been found in Obora, Czech Republic and Tshekarda in the Ural mountains, Russia. However, there are only a few fossils from North America before the
middle Permian The Guadalupian is the second and middle series/epoch of the Permian. The Guadalupian was preceded by the Cisuralian and followed by the Lopingian. It is named after the Guadalupe Mountains of New Mexico and Texas, and dates between 272.95 ± 0. ...
, although both Asia and North America had been united to
Euramerica Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around ( Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during the breakup of Pan ...
. The first discoveries from North America made in the Wellington Formation of Oklahoma were published in 2005 and 2008. The earliest members of modern beetle lineages appeared during the Late Permian. In the
Permian–Triassic extinction event The Permian–Triassic (P–T, P–Tr) extinction event, also known as the Latest Permian extinction event, the End-Permian Extinction and colloquially as the Great Dying, formed the boundary between the Permian and Triassic geologic periods, as ...
at the end of the Permian, most "protocoleopteran" lineages became extinct. Beetle diversity did not recover to pre-extinction levels until the
Middle Triassic In the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided in chronostratigraphy. The Middle Triassic spans the time between Ma and ...
.


Jurassic

During the
Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...
(), there was a dramatic increase in the diversity of beetle families, including the development and growth of carnivorous and herbivorous species. The
Chrysomeloidea The Chrysomeloidea are an enormous superfamily of beetles, with tens of thousands of species. The largest families are Cerambycidae, long-horned beetles, with more than 35,000 species, and Chrysomelidae, leaf beetles, with more than 13,000 specie ...
diversified around the same time, feeding on a wide array of plant hosts from
cycad Cycads are seed plants that typically have a stout and woody (ligneous) trunk (botany), trunk with a crown (botany), crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants o ...
s and
conifer Conifers are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single ...
s to
angiosperm Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...
s. McHugh (2009), p. 186 Close to the Upper Jurassic, the Cupedidae decreased, but the diversity of the early plant-eating species increased. Most recent plant-eating beetles feed on flowering plants or angiosperms, whose success contributed to a doubling of plant-eating species during the
Middle Jurassic The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations co ...
. However, the increase of the number of beetle families during the Cretaceous does not correlate with the increase of the number of angiosperm species. Around the same time, numerous primitive weevils (e.g.
Curculionoidea Weevils are beetles belonging to the Taxonomic rank, superfamily Curculionoidea, known for their elongated snouts. They are usually small, less than in length, and Herbivore, herbivorous. Approximately 97,000 species of weevils are known. They b ...
) and click beetles (e.g. Elateroidea) appeared. The first jewel beetles (e.g.
Buprestidae Buprestidae is a family of beetles known as jewel beetles or metallic wood-boring beetles because of their glossy iridescent colors. Larvae of this family are known as flatheaded borers. The family is among the largest of the beetles, with some ...
) are present, but they remained rare until the Cretaceous. The first scarab beetles were not coprophagous but presumably fed on rotting wood with the help of fungus; they are an early example of a mutualistic relationship. There are more than 150 important fossil sites from the Jurassic, the majority in Eastern Europe and North Asia. Outstanding sites include
Solnhofen Solnhofen is a municipality in the district of Weißenburg-Gunzenhausen in the region of Middle Franconia in the ' of Bavaria in Germany. It is in the Altmühl valley. The local area is famous in geology and palaeontology for Solnhofen limest ...
in Upper
Bavaria Bavaria ( ; ), officially the Free State of Bavaria (german: Freistaat Bayern, link=no ), is a state in the south-east of Germany. With an area of , Bavaria is the largest German state by land area, comprising roughly a fifth of the total lan ...
, Germany, Karatau in South
Kazakhstan Kazakhstan, officially the Republic of Kazakhstan, is a transcontinental country located mainly in Central Asia and partly in Eastern Europe. It borders Russia to the north and west, China to the east, Kyrgyzstan to the southeast, Uzbeki ...
, the Yixian formation in
Liaoning Liaoning () is a coastal province in Northeast China that is the smallest, southernmost, and most populous province in the region. With its capital at Shenyang, it is located on the northern shore of the Yellow Sea, and is the northernmost ...
, North China, as well as the Jiulongshan formation and further fossil sites in
Mongolia Mongolia; Mongolian script: , , ; lit. "Mongol Nation" or "State of Mongolia" () is a landlocked country in East Asia, bordered by Russia to the north and China to the south. It covers an area of , with a population of just 3.3 million, ...
. In North America there are only a few sites with fossil records of insects from the Jurassic, namely the shell limestone deposits in the Hartford basin, the Deerfield basin and the Newark basin.


Cretaceous

The
Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...
saw the fragmenting of the southern landmass, with the opening of the southern Atlantic Ocean and the isolation of New Zealand, while South America, Antarctica, and Australia grew more distant. The diversity of Cupedidae and
Archostemata The Archostemata are the smallest suborder of beetles, consisting 45 living species in five families. They are an ancient lineage with a number of primitive characteristics. Antennae may be thread-shaped (filiform) or like a string of beads (mon ...
decreased considerably. Predatory ground beetles (Carabidae) and rove beetles (Staphylinidae) began to distribute into different patterns; the Carabidae predominantly occurred in the warm regions, while the
Staphylinidae The rove beetles are a family (Staphylinidae) of beetles, primarily distinguished by their short elytra (wing covers) that typically leave more than half of their abdominal segments exposed. With roughly 63,000 species in thousands of genera, the ...
and click beetles (Elateridae) preferred temperate climates. Likewise, predatory species of
Cleroidea Cleroidea is a small superfamily of beetles containing over 10,000 species. Most of the members of the group are somewhat slender, often with fairly soft, flexible elytra, and typically hairy or scaly. Description Cleroidea is defined by the fo ...
and
Cucujoidea Cucujoidea is a superfamily of beetles. This group formerly included all of the families now included in the superfamily Coccinelloidea. They include some fungus beetles and a diversity of lineages of "bark beetles" unrelated to the "true" bark ...
hunted their prey under the bark of trees together with the
jewel beetle Buprestidae is a family of beetles known as jewel beetles or metallic wood-boring beetles because of their glossy iridescent colors. Larvae of this family are known as flatheaded borers. The family is among the largest of the beetles, with some ...
s (Buprestidae). The diversity of jewel beetles increased rapidly, as they were the primary consumers of wood, while
longhorn beetle The longhorn beetles (Cerambycidae), also known as long-horned or longicorns, are a large family of beetles, with over 35,000 species described. Most species are characterized by extremely long antennae, which are often as long as or longer than ...
s ( Cerambycidae) were rather rare: their diversity increased only towards the end of the Upper Cretaceous. The first coprophagous beetles are from the Upper Cretaceous and may have lived on the excrement of herbivorous dinosaurs. The first species where both larvae and adults are adapted to an aquatic lifestyle are found. Whirligig beetles (Gyrinidae) were moderately diverse, although other early beetles (e.g. Dytiscidae) were less, with the most widespread being the species of Coptoclavidae, which preyed on aquatic fly larvae. A 2020 review of the palaeoecological interpretations of fossil beetles from Cretaceous ambers has suggested that
saproxylic Xylophagy is a term used in ecology to describe the habits of an herbivorous animal whose diet consists primarily (often solely) of wood. The word derives from Greek ''ξυλοφάγος'' (''xulophagos'') "eating wood", from ''ξύλον'' (') ...
ity was the most common feeding strategy, with
fungivorous Fungivory or mycophagy is the process of organisms consuming fungi. Many different organisms have been recorded to gain their energy from consuming fungi, including birds, mammals, insects, plants, amoebas, gastropods, nematodes, bacteria and othe ...
species in particular appearing to dominate. Many fossil sites worldwide contain beetles from the Cretaceous. Most are in Europe and Asia and belong to the temperate climate zone during the Cretaceous. Lower Cretaceous sites include the Crato fossil beds in the Araripe basin in the
Ceará Ceará (, pronounced locally as or ) is one of the 26 states of Brazil, located in the northeastern part of the country, on the Atlantic coast. It is the eighth-largest Brazilian State by population and the 17th by area. It is also one of the ...
, North Brazil, as well as overlying Santana formation; the latter was near the equator at that time. In Spain, important sites are near
Montsec The Montsec Range ( ca, Serra del Montsec ; es, Sierra del Montsec) is a mountain system of the Pre-Pyrenees. Description The Serra del Montsec consists of a series of calcareous mountain ranges running roughly from east to west. The range syste ...
and Las Hoyas. In Australia, the Koonwarra fossil beds of the Korumburra group,
South Gippsland South Gippsland, a region of Gippsland in Victoria, Australia, is a well-watered region consisting of low, rolling hills descending to the coast in the south and the Latrobe Valley in the north. Low granite hills continue into Wilsons Promonto ...
, Victoria, are noteworthy. Major sites from the Upper Cretaceous include Kzyl-Dzhar in South Kazakhstan and Arkagala in Russia.


Cenozoic

Beetle fossils are abundant in the Cenozoic; by the
Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...
(up to 1.6 mya), fossil species are identical to living ones, while from the
Late Miocene The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million ye ...
(5.7 mya) the fossils are still so close to modern forms that they are most likely the ancestors of living species. The large oscillations in climate during the Quaternary caused beetles to change their geographic distributions so much that current location gives little clue to the biogeographical history of a species. It is evident that geographic isolation of populations must often have been broken as insects moved under the influence of changing climate, causing mixing of gene pools, rapid evolution, and extinctions, especially in middle latitudes.


Phylogeny

The very large number of beetle species poses special problems for
classification Classification is a process related to categorization, the process in which ideas and objects are recognized, differentiated and understood. Classification is the grouping of related facts into classes. It may also refer to: Business, organizat ...
. Some families contain tens of thousands of species, and need to be divided into subfamilies and tribes. This immense number led the evolutionary biologist
J. B. S. Haldane John Burdon Sanderson Haldane (; 5 November 18921 December 1964), nicknamed "Jack" or "JBS", was a British-Indian scientist who worked in physiology, genetics, evolutionary biology, and mathematics. With innovative use of statistics in biolog ...
to quip, when some
theologians Theology is the systematic study of the nature of the divine and, more broadly, of religious belief. It is taught as an academic discipline, typically in universities and seminaries. It occupies itself with the unique content of analyzing the s ...
asked him what could be inferred about the mind of the
Christian God God in Christianity is believed to be the eternal, supreme being who created and preserves all things. Christians believe in a monotheistic conception of God, which is both transcendent (wholly independent of, and removed from, the material u ...
from the works of His Creation, "An inordinate fondness for beetles".
Polyphaga Polyphaga is the largest and most diverse suborder of beetles. It comprises 144 families in 16 superfamilies, and displays an enormous variety of specialization and adaptation, with over 350,000 described species, or approximately 90% of the b ...
is the largest suborder, containing more than 300,000 described species in more than 170 families, including
rove beetle The rove beetles are a family (Staphylinidae) of beetles, primarily distinguished by their short elytra (wing covers) that typically leave more than half of their abdominal segments exposed. With roughly 63,000 species in thousands of genera, the ...
s (Staphylinidae), scarab beetles ( Scarabaeidae),
blister beetle Blister beetles are beetles of the family Meloidae, so called for their defensive secretion of a blistering agent, cantharidin. About 7,500 species are known worldwide. Many are conspicuous and some are aposematically colored, announcing their ...
s (Meloidae),
stag beetle Stag beetles are a family of about 1,200 species of beetles in the family Lucanidae, currently classified in four subfamilies.Smith, A.B.T. (2006). A review of the family-group names for the superfamily Scarabaeoidea (Coleoptera) with corrections ...
s (Lucanidae) and true weevils (
Curculionidae The Curculionidae are a family of weevils, commonly called snout beetles or true weevils. They are one of the largest animal families, with 6,800 genera and 83,000 species described worldwide. They are the sister group to the family Brentidae. T ...
). These polyphagan beetle groups can be identified by the presence of cervical sclerites (hardened parts of the head used as points of attachment for muscles) absent in the other suborders.
Adephaga The Adephaga (from Greek ἀδηφάγος, ''adephagos'', "gluttonous") are a suborder of beetles, and with more than 40,000 recorded species in 10 families, the second-largest of the four beetle suborders. Members of this suborder are collect ...
contains about 10 families of largely predatory beetles, includes
ground beetle Ground beetles are a large, cosmopolitan distribution, cosmopolitan family (biology), family of beetles, the Carabidae, with more than 40,000 species worldwide, around 2,000 of which are found in North America and 2,700 in Europe. As of 2015, it i ...
s (Carabidae), water beetles ( Dytiscidae) and whirligig beetles (Gyrinidae). In these insects, the
testes A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testoster ...
are tubular and the first abdominal sternum (a plate of the
exoskeleton An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton (endoskeleton) in for example, a human. In usage, some of the ...
) is divided by the hind coxae (the basal joints of the beetle's legs).
Archostemata The Archostemata are the smallest suborder of beetles, consisting 45 living species in five families. They are an ancient lineage with a number of primitive characteristics. Antennae may be thread-shaped (filiform) or like a string of beads (mon ...
contains four families of mainly wood-eating beetles, including
reticulated beetle The Cupedidae are a small family (biology), family of beetles, notable for the square pattern of "windows" on their elytra (hard forewings), which give the family their common name of reticulated beetles. The family consists of about 30 species ...
s (Cupedidae) and the
telephone-pole beetle The telephone-pole beetle (''Micromalthus debilis'') is a beetle native to the eastern United States, and the only living representative of the otherwise extinct family Micromalthidae. They have an unusual lifecycle involving asexually reproducin ...
. The Archostemata have an exposed plate called the metatrochantin in front of the basal segment or coxa of the hind leg. Myxophaga contains about 65 described species in four families, mostly very small, including Hydroscaphidae and the genus ''
Sphaerius ''Sphaerius'' is a genus of beetles, comprising 23 species, which are the only living members of the family Sphaeriusidae. They are typically found along the edges of streams and rivers, where they feed on algae; they occur on all continents ex ...
''. The myxophagan beetles are small and mostly alga-feeders. Their mouthparts are characteristic in lacking galeae and having a mobile tooth on their left mandible. The consistency of beetle
morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...
, in particular their possession of elytra, has long suggested that Coleoptera is
monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...
, though there have been doubts about the arrangement of the
suborders Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...
, namely the
Adephaga The Adephaga (from Greek ἀδηφάγος, ''adephagos'', "gluttonous") are a suborder of beetles, and with more than 40,000 recorded species in 10 families, the second-largest of the four beetle suborders. Members of this suborder are collect ...
,
Archostemata The Archostemata are the smallest suborder of beetles, consisting 45 living species in five families. They are an ancient lineage with a number of primitive characteristics. Antennae may be thread-shaped (filiform) or like a string of beads (mon ...
, Myxophaga and
Polyphaga Polyphaga is the largest and most diverse suborder of beetles. It comprises 144 families in 16 superfamilies, and displays an enormous variety of specialization and adaptation, with over 350,000 described species, or approximately 90% of the b ...
within that
clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...
. The twisted-wing parasites, Strepsiptera, are thought to be a sister group to the beetles, having split from them in the
Early Permian 01 or '01 may refer to: * The year 2001, or any year ending with 01 * The month of January * 1 (number) Music * '01 (Richard Müller album), 01'' (Richard Müller album), 2001 * 01 (Son of Dave album), ''01'' (Son of Dave album), 2000 * 01 (Urban ...
. Molecular phylogenetic analysis confirms that the Coleoptera are monophyletic. Duane McKenna et al. (2015) used eight nuclear genes for 367 species from 172 of 183 Coleopteran families. They split the Adephaga into 2 clades, Hydradephaga and Geadephaga, broke up the Cucujoidea into 3 clades, and placed the Lymexyloidea within the Tenebrionoidea. The Polyphaga appear to date from the Triassic. Most extant beetle families appear to have arisen in the Cretaceous. The cladogram is based on McKenna (2015). The number of species in each group (mainly superfamilies) is shown in parentheses, and boldface if over 10,000. English common names are given where possible. Dates of origin of major groups are shown in italics in millions of years ago (mya).


External morphology

Beetles are generally characterized by a particularly hard
exoskeleton An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton (endoskeleton) in for example, a human. In usage, some of the ...
and hard forewings ( elytra) not usable for flying. Almost all beetles have mandibles that move in a horizontal plane. The mouthparts are rarely suctorial, though they are sometimes reduced; the maxillae always bear palps. The antennae usually have 11 or fewer segments, except in some groups like the Cerambycidae (longhorn beetles) and the Rhipiceridae (cicada parasite beetles). The coxae of the legs are usually located recessed within a coxal cavity. The genitalic structures are telescoped into the last abdominal segment in all extant beetles. Beetle larvae can often be confused with those of other endopterygote groups. The beetle's exoskeleton is made up of numerous plates, called sclerites, separated by thin sutures. This design provides armored defenses while maintaining flexibility. The general
anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its ...
of a beetle is quite uniform, although specific organs and
appendage An appendage (or outgrowth) is an external body part, or natural prolongation, that protrudes from an organism's body. In arthropods, an appendage refers to any of the homologous body parts that may extend from a body segment, including anten ...
s vary greatly in appearance and function between the many families in the order. Like all insects, beetles' bodies are divided into three sections: the head, the thorax, and the abdomen. Because there are so many species, identification is quite difficult, and relies on attributes including the shape of the antennae, the
tarsal formula Tarsal formula is the number of segments of the tarsi, which has 3 numbers a-b-c, starting with the fore leg (a), then the middle leg (b), then the hind leg (c). For example, a tarsal formula of "5-5-4" as found in the Trictenotomidae means the ...
e and shapes of these small segments on the legs, the mouthparts, and the ventral plates (sterna, pleura, coxae). In many species accurate identification can only be made by examination of the unique male genitalic structures.


Head

The head, having mouthparts projecting forward or sometimes downturned, is usually heavily sclerotized and is sometimes very large. The eyes are compound and may display remarkable adaptability, as in the case of the aquatic whirligig beetles ( Gyrinidae), where they are split to allow a view both above and below the waterline. A few
Longhorn beetle The longhorn beetles (Cerambycidae), also known as long-horned or longicorns, are a large family of beetles, with over 35,000 species described. Most species are characterized by extremely long antennae, which are often as long as or longer than ...
s ( Cerambycidae) and weevils as well as some fireflies ( Rhagophthalmidae) have divided eyes, while many have eyes that are notched, and a few have ocelli, small, simple
eye Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...
s usually farther back on the head (on the
vertex Vertex, vertices or vertexes may refer to: Science and technology Mathematics and computer science *Vertex (geometry), a point where two or more curves, lines, or edges meet *Vertex (computer graphics), a data structure that describes the position ...
); these are more common in larvae than in adults. The anatomical organization of the compound eyes may be modified and depends on whether a species is primarily crepuscular, or diurnally or nocturnally active. Ocelli are found in the adult carpet beetle ( Dermestidae), some rove beetles (
Omaliinae The Omaliinae are a subfamily of the Staphylinidae, rove beetles.Newton, A. F., Jr., M. K. Thayer, J. S. Ashe, and D. S. Chandler. 2001. 22. Staphylinidae Latreille, 1802. p. 272–418. In: R. H. Arnett, Jr., and M. C. Thomas (eds.). American bee ...
), and the
Derodontidae Derodontidae is a family of beetles, in its own superfamily, Derodontoidea, sometimes known as the tooth-necked fungus beetles. Beetles of this family are small, between 2 and 6 mm in length, typically with spiny margins on their pronotum (p ...
. Beetle antennae are primarily organs of sensory perception and can detect motion, odor and chemical substances, but may also be used to physically feel a beetle's environment. Beetle families may use antennae in different ways. For example, when moving quickly, tiger beetles may not be able to see very well and instead hold their antennae rigidly in front of them in order to avoid obstacles. Certain Cerambycidae use antennae to balance, and blister beetles may use them for grasping. Some aquatic beetle species may use antennae for gathering air and passing it under the body whilst submerged. Equally, some families use antennae during mating, and a few species use them for defense. In the cerambycid ''
Onychocerus albitarsis ''Onychocerus albitarsis'' is a relatively rare species of beetle in the family Cerambycidae from the Amazon and Atlantic forest regions in Brazil, Bolivia, Paraguay and southern Peru. It is remarkable for being the only known beetle that has a ...
'', the antennae have venom injecting structures used in defense, which is unique among
arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...
s. Antennae vary greatly in form, sometimes between the sexes, but are often similar within any given family. Antennae may be
clubbed ''Clubbed'' is a 2008 British drama film about a 1980s factory worker who takes up a job as a club doorman, written by Geoff Thompson and directed by Neil Thompson. Plot In 1984, Danny - a lonely factory worker intimidated by life - is batter ...
, threadlike, angled, shaped like a string of beads, comb-like (either on one side or both, bipectinate), or toothed. The physical variation of antennae is important for the identification of many beetle groups. The Curculionidae have elbowed or geniculate antennae. Feather like flabellate antennae are a restricted form found in the Rhipiceridae and a few other families. The Silphidae have a capitate antennae with a spherical head at the tip. The Scarabaeidae typically have lamellate antennae with the terminal segments extended into long flat structures stacked together. The Carabidae typically have thread-like antennae. The antennae arises between the eye and the mandibles and in the Tenebrionidae, the antennae rise in front of a notch that breaks the usually circular outline of the compound eye. They are segmented and usually consist of 11 parts, the first part is called the scape and the second part is the pedicel. The other segments are jointly called the flagellum. Beetles have mouthparts like those of
grasshopper Grasshoppers are a group of insects belonging to the suborder Caelifera. They are among what is possibly the most ancient living group of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago. Grasshopp ...
s. The mandibles appear as large pincers on the front of some beetles. The mandibles are a pair of hard, often tooth-like structures that move horizontally to grasp, crush, or cut food or enemies (see
defence Defense or defence may refer to: Tactical, martial, and political acts or groups * Defense (military), forces primarily intended for warfare * Civil defense, the organizing of civilians to deal with emergencies or enemy attacks * Defense industr ...
, below). Two pairs of finger-like appendages, the maxillary and labial palpi, are found around the mouth in most beetles, serving to move food into the mouth. In many species, the mandibles are sexually dimorphic, with those of the males enlarged enormously compared with those of females of the same species.


Thorax

The thorax is segmented into the two discernible parts, the pro- and pterothorax. The pterothorax is the fused meso- and metathorax, which are commonly separated in other insect species, although flexibly articulate from the prothorax. When viewed from below, the thorax is that part from which all three pairs of legs and both pairs of wings arise. The abdomen is everything posterior to the thorax. When viewed from above, most beetles appear to have three clear sections, but this is deceptive: on the beetle's upper surface, the middle section is a hard plate called the pronotum, which is only the front part of the thorax; the back part of the thorax is concealed by the beetle's wings. This further segmentation is usually best seen on the abdomen.


Legs

The multisegmented
legs A leg is a weight-bearing and locomotive anatomical structure, usually having a columnar shape. During locomotion, legs function as "extensible struts". The combination of movements at all joints can be modeled as a single, linear element ...
end in two to five small segments called tarsi. Like many other insect orders, beetles have claws, usually one pair, on the end of the last tarsal segment of each leg. While most beetles use their legs for walking, legs have been variously adapted for other uses. Aquatic beetles including the Dytiscidae (diving beetles), Haliplidae, and many species of
Hydrophilidae Hydrophilidae, also known colloquially as water scavenger beetles, is a family of beetles. Aquatic hydrophilids are notable for their long maxillary palps, which are longer than their antennae. Several of the former subfamilies of Hydrophilidae ...
, the legs, often the last pair, are modified for swimming, typically with rows of long hairs. Male diving beetles have suctorial cups on their forelegs that they use to grasp females. Other beetles have
fossorial A fossorial () animal is one adapted to digging which lives primarily, but not solely, underground. Some examples are badgers, naked mole-rats, clams, meerkats, and mole salamanders, as well as many beetles, wasps, and bees. Prehistoric eviden ...
legs widened and often spined for digging. Species with such adaptations are found among the scarabs, ground beetles, and
clown beetle Histeridae is a family (biology), family of beetles commonly known as clown beetles or Hister beetles. This very diverse group of beetles contains 3,900 species found worldwide. They can be easily identified by their shortened elytra that leaves ...
s ( Histeridae). The hind legs of some beetles, such as flea beetles (within Chrysomelidae) and flea weevils (within Curculionidae), have enlarged femurs that help them leap.


Wings

The forewings of beetles are not used for flight, but form elytra which cover the hind part of the body and protect the hindwings. The elytra are usually hard shell-like structures which must be raised to allow the hindwings to move for flight. However, in the soldier beetles (
Cantharidae The soldier beetles (Cantharidae) are relatively soft-bodied, straight-sided beetles. They are cosmopolitan in distribution. One of the first described species has a color pattern reminiscent of the Red coat (British army), red coats of early Bri ...
), the elytra are soft, earning this family the name of leatherwings. Other soft wing beetles include the
net-winged beetle The Lycidae are a family in the beetle order Coleoptera, members of which are commonly called net-winged beetles. These beetles are cosmopolitan, being found in Nearctic, Palearctic, Neotropical, Afrotropical, Oriental, and Australian ecoregion ...
''
Calopteron discrepans ''Calopteron discrepans'', the banded net-winged beetle, is a species of net-winged beetle in the family Lycidae The Lycidae are a family in the beetle order Coleoptera, members of which are commonly called net-winged beetles. These beetles a ...
'', which has brittle wings that rupture easily in order to release chemicals for defense. Beetles' flight wings are crossed with veins and are folded after landing, often along these veins, and stored below the elytra. A fold (''jugum'') of the membrane at the base of each wing is characteristic. Some beetles have lost the ability to fly. These include some ground beetles (Carabidae) and some true weevils (Curculionidae), as well as desert- and cave-dwelling species of other families. Many have the two elytra fused together, forming a solid shield over the abdomen. In a few families, both the ability to fly and the elytra have been lost, as in the
glow-worm Glowworm or glow-worm is the common name for various groups of insect larvae and adult larviform females that glow through bioluminescence. They include the European common glow-worm and other members of the Lampyridae, but bioluminescence also o ...
s (
Phengodidae The beetle family Phengodidae is known also as glowworm beetles, whose larvae are known as glowworms. The females and larvae have bioluminescence, bioluminescent organs. They occur throughout the New World from extreme southern Canada to Chile. ...
), where the females resemble larvae throughout their lives. The presence of elytra and wings does not always indicate that the beetle will fly. For example, the
tansy beetle The tansy beetle (''Chrysolina graminis'') is a species of leaf beetle. It measures 7.7–10.5 mm in length and has a characteristic bright metallic green colouration. The common name derives from the tansy plant on which they often feed ...
walks between habitats despite being physically capable of flight.


Abdomen

The
abdomen The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...
is the section behind the metathorax, made up of a series of rings, each with a hole for breathing and respiration, called a
spiracle Spiracle or spiraculum may refer to: * Spiracle (arthropods), opening in the exoskeletons of some arthropods * Spiracle (vertebrates), openings on the surface of some vertebrates * Spiraculum, a genus of land snails in family Cyclophoridae Cycl ...
, composing three different segmented sclerites: the tergum, pleura, and the sternum. The tergum in almost all species is membranous, or usually soft and concealed by the wings and elytra when not in flight. The pleura are usually small or hidden in some species, with each pleuron having a single spiracle. The sternum is the most widely visible part of the abdomen, being a more or less sclerotized segment. The abdomen itself does not have any appendages, but some (for example,
Mordellidae The Mordellidae are a family of beetles commonly known as tumbling flower beetles for the typical irregular movements they make when escaping predators, or as pintail beetles due to their abdominal tip which aids them in performing these tumbling ...
) have articulating sternal lobes.


Anatomy and physiology


Digestive system

The
digestive system The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food into smaller and smaller compone ...
of beetles is primarily adapted for a herbivorous diet. Digestion takes place mostly in the anterior midgut, although in predatory groups like the Carabidae, most digestion occurs in the crop by means of midgut enzymes. In the Elateridae, the larvae are liquid feeders that extraorally digest their food by secreting enzymes. The alimentary canal basically consists of a short, narrow
pharynx The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its struc ...
, a widened expansion, the crop, and a poorly developed gizzard. This is followed by the midgut, that varies in dimensions between species, with a large amount of cecum, and the hindgut, with varying lengths. There are typically four to six Malpighian tubules.


Nervous system

The
nervous system In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes th ...
in beetles contains all the types found in insects, varying between different species, from three thoracic and seven or eight abdominal ganglia which can be distinguished to that in which all the thoracic and abdominal ganglia are fused to form a composite structure.


Respiratory system

Like most insects, beetles inhale air, for the
oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
it contains, and exhale
carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
, via a tracheal system. Air enters the body through
spiracle Spiracle or spiraculum may refer to: * Spiracle (arthropods), opening in the exoskeletons of some arthropods * Spiracle (vertebrates), openings on the surface of some vertebrates * Spiraculum, a genus of land snails in family Cyclophoridae Cycl ...
s, and circulates within the haemocoel in a system of
tracheae The trachea, also known as the windpipe, is a cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all air- breathing animals with lungs. The trachea extends from the ...
and tracheoles, through whose walls the gases can diffuse. Diving beetles, such as the Dytiscidae, carry a bubble of air with them when they dive. Such a bubble may be contained under the elytra or against the body by specialized
hydrophobic In chemistry, hydrophobicity is the physical property of a molecule that is seemingly repelled from a mass of water (known as a hydrophobe). In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, th ...
hairs. The bubble covers at least some of the spiracles, permitting air to enter the tracheae. The function of the bubble is not only to contain a store of air but to act as a physical gill. The air that it traps is in contact with oxygenated water, so as the animal's consumption depletes the oxygen in the bubble, more oxygen can diffuse in to replenish it. Carbon dioxide is more soluble in water than either oxygen or nitrogen, so it readily diffuses out faster than in. Nitrogen is the most plentiful gas in the bubble, and the least soluble, so it constitutes a relatively static component of the bubble and acts as a stable medium for respiratory gases to accumulate in and pass through. Occasional visits to the surface are sufficient for the beetle to re-establish the constitution of the bubble.


Circulatory system

Like other insects, beetles have
open circulatory system The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
s, based on
hemolymph Hemolymph, or haemolymph, is a fluid, analogous to the blood in vertebrates, that circulates in the interior of the arthropod (invertebrate) body, remaining in direct contact with the animal's tissues. It is composed of a fluid plasma in which ...
rather than blood. As in other insects, a segmented tube-like heart is attached to the dorsal wall of the
hemocoel The blood circulatory system is a organ system, system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascula ...
. It has paired inlets or ''ostia'' at intervals down its length, and circulates the hemolymph from the main cavity of the haemocoel and out through the anterior cavity in the head.


Specialized organs

Different glands are specialized for different pheromones to attract mates. Pheromones from species of
Rutelinae Rutelinae or shining leaf chafers is a subfamily of the scarab beetles (family Scarabaeidae). It is a very diverse group; distributed over most of the world, it contains some 200 genera with over 4,000 described species in 7 tribes. A few recent ...
are produced from
epithelial cell Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellula ...
s lining the inner surface of the apical abdominal segments; amino acid-based pheromones of
Melolonthinae Melolonthinae is a subfamily of the scarab beetles (family Scarabaeidae). It is a very diverse group; distributed over most of the world, it contains over 11,000 species in over 750 genera. Some authors include the scarab subfamilies Euchirinae ...
are produced from eversible glands on the abdominal apex. Other species produce different types of pheromones.
Dermestid Dermestidae are a family of Coleoptera that are commonly referred to as skin beetles. Other common names include larder beetle, hide or leather beetles, carpet beetles, and khapra beetles. There are over 1,100 species described. Dermestids have ...
s produce
ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ar ...
s, and species of Elateridae produce fatty acid-derived aldehydes and
acetate An acetate is a salt (chemistry), salt formed by the combination of acetic acid with a base (e.g. Alkali metal, alkaline, Alkaline earth metal, earthy, Transition metal, metallic, nonmetallic or radical Radical (chemistry), base). "Acetate" als ...
s. To attract a mate, fireflies ( Lampyridae) use modified fat body cells with transparent surfaces backed with reflective uric acid crystals to produce light by
bioluminescence Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some b ...
. Light production is highly efficient, by oxidation of luciferin catalyzed by enzymes (
luciferase Luciferase is a generic term for the class of oxidative enzymes that produce bioluminescence, and is usually distinguished from a photoprotein. The name was first used by Raphaël Dubois who invented the words ''luciferin'' and ''luciferase'', ...
s) in the presence of
adenosine triphosphate Adenosine triphosphate (ATP) is an organic compound that provides energy to drive many processes in living cells, such as muscle contraction, nerve impulse propagation, condensate dissolution, and chemical synthesis. Found in all known forms of ...
(ATP) and oxygen, producing
oxyluciferin Luciferin (from the Latin ''lucifer'', "light-bearer") is a generic term for the light-emitting compound found in organisms that generate bioluminescence. Luciferins typically undergo an enzyme-catalyzed reaction with molecular oxygen. The result ...
, carbon dioxide, and light.
Tympanal organ A tympanal organ (or tympanic organ) is a hearing organ in insects, consisting of a membrane ( tympanum) stretched across a frame backed by an air sac and associated sensory neurons. Sounds vibrate the membrane, and the vibrations are sensed by ...
s or hearing organs consist of a membrane (tympanum) stretched across a frame backed by an air sac and associated sensory neurons, are found in two families. Several species of the genus '' Cicindela'' (Carabidae) have hearing organs on the dorsal surfaces of their first abdominal segments beneath the wings; two tribes in the Dynastinae (within the Scarabaeidae) have hearing organs just beneath their pronotal shields or neck membranes. Both families are sensitive to ultrasonic frequencies, with strong evidence indicating they function to detect the presence of bats by their ultrasonic echolocation.


Reproduction and development

Beetles are members of the
superorder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...
Endopterygota Endopterygota (from Ancient Greek ''endon'' 'inner' + ''pterón'' 'wing' + New Latin ''-ota'' 'having'), also known as Holometabola, is a superorder of insects within the infraclass Neoptera that go through distinctive larval, pupal, and adult s ...
, and accordingly most of them undergo complete
metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some inse ...
. The typical form of metamorphosis in beetles passes through four main stages: the
egg An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the a ...
, the
larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...
, the
pupa A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...
, and the
imago In biology, the imago (Latin for "image") is the last stage an insect attains during its metamorphosis, its process of growth and development; it is also called the imaginal stage, the stage in which the insect attains maturity. It follows the f ...
or adult. The larvae are commonly called grubs and the pupa sometimes is called the chrysalis. In some species, the pupa may be enclosed in a cocoon constructed by the larva towards the end of its final
instar An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ass ...
. Some beetles, such as typical members of the families Meloidae and
Rhipiphoridae Ripiphoridae (formerly spelled Rhipiphoridae) is a cosmopolitan family of some 450 described species of Beetle, beetles sometimes Common name, called "wedge-shaped beetles". Ripiphoridae are unusual among beetle families in that many species are ...
, go further, undergoing
hypermetamorphosis Hypermetamorphosis, or heteromorphosis,P.J. Gullan & P.S. Cranston. 2010. The Insects: An Outline of Entomology, 4th Edition. Wiley-Blackwell. is a term used in entomology that refers to a class of variants of holometabolism, that is to say, com ...
in which the first instar takes the form of a triungulin.


Mating

Some beetles have intricate mating behaviour. Pheromone communication is often important in locating a mate. Different species use different pheromones. Scarab beetles such as the
Rutelinae Rutelinae or shining leaf chafers is a subfamily of the scarab beetles (family Scarabaeidae). It is a very diverse group; distributed over most of the world, it contains some 200 genera with over 4,000 described species in 7 tribes. A few recent ...
use pheromones derived from
fatty acid synthesis In biochemistry, fatty acid synthesis is the creation of fatty acids from acetyl-CoA and NADPH through the action of enzymes called fatty acid synthases. This process takes place in the cytoplasm of the cell. Most of the acetyl-CoA which is conve ...
, while other scarabs such as the
Melolonthinae Melolonthinae is a subfamily of the scarab beetles (family Scarabaeidae). It is a very diverse group; distributed over most of the world, it contains over 11,000 species in over 750 genera. Some authors include the scarab subfamilies Euchirinae ...
use
amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...
s and terpenoids. Another way beetles find mates is seen in the fireflies (Lampyridae) which are
bioluminescent Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some Fungus, fungi, microorganisms including ...
, with abdominal light-producing organs. The males and females engage in a complex dialog before mating; each species has a unique combination of flight patterns, duration, composition, and intensity of the light produced. Before mating, males and females may stridulate, or vibrate the objects they are on. In the Meloidae, the male climbs onto the dorsum of the female and strokes his antennae on her head, palps, and antennae. In ''
Eupompha ''Eupompha'' is a genus of blister beetles in the family Meloidae Blister beetles are beetles of the family Meloidae, so called for their defensive secretion of a blistering agent, cantharidin. About 7,500 species are known worldwide. Many ar ...
'', the male draws his antennae along his longitudinal vertex. They may not mate at all if they do not perform the precopulatory ritual. This mating behavior may be different amongst dispersed populations of the same species. For example, the mating of a
Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...
n population of
tansy beetle The tansy beetle (''Chrysolina graminis'') is a species of leaf beetle. It measures 7.7–10.5 mm in length and has a characteristic bright metallic green colouration. The common name derives from the tansy plant on which they often feed ...
(''Chysolina graminis'') is preceded by an elaborate ritual involving the male tapping the female's eyes, pronotum and antennae with its antennae, which is not evident in the population of this species in the
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...
.
Competition Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, indivi ...
can play a part in the mating rituals of species such as burying beetles (''Nicrophorus''), the insects fighting to determine which can mate. Many male beetles are
territorial A territory is an area of land, sea, or space, particularly belonging or connected to a country, person, or animal. In international politics, a territory is usually either the total area from which a state may extract power resources or a ...
and fiercely defend their territories from intruding males. In such species, the male often has horns on the head or thorax, making its body length greater than that of a female. Copulation is generally quick, but in some cases lasts for several hours. During copulation,
sperm cell Sperm is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm with a tail known as a flagellum, whi ...
s are transferred to the female to
fertilize Fertilisation or fertilization (see spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a new individual organism or offspring and initiate its development. Proce ...
the egg.


Life cycle


Egg

Essentially all beetles lay eggs, though some myrmecophilous Aleocharinae and some Chrysomelinae which live in mountains or the subarctic are
ovoviviparous Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop insi ...
, laying eggs which hatch almost immediately. Beetle eggs generally have smooth surfaces and are soft, though the Cupedidae have hard eggs. Eggs vary widely between species: the eggs tend to be small in species with many instars (larval stages), and in those that lay large numbers of eggs. A female may lay from several dozen to several thousand eggs during her lifetime, depending on the extent of parental care. This ranges from the simple laying of eggs under a leaf, to the parental care provided by scarab beetles, which house, feed and protect their young. The Attelabidae roll leaves and lay their eggs inside the roll for protection.


Larva

The
larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...
is usually the principal feeding stage of the beetle life cycle. Larvae tend to feed voraciously once they emerge from their eggs. Some feed externally on plants, such as those of certain leaf beetles, while others feed within their food sources. Examples of internal feeders are most
Buprestidae Buprestidae is a family of beetles known as jewel beetles or metallic wood-boring beetles because of their glossy iridescent colors. Larvae of this family are known as flatheaded borers. The family is among the largest of the beetles, with some ...
and longhorn beetles. The larvae of many beetle families are predatory like the adults (ground beetles, ladybirds, rove beetles). The larval period varies between species, but can be as long as several years. The larvae of
skin beetle Dermestidae are a family of Coleoptera that are commonly referred to as skin beetles. Other common names include larder beetle, hide or leather beetles, carpet beetles, and khapra beetles. There are over 1,100 species described. Dermestids have ...
s undergo a degree of reversed development when starved, and later grow back to the previously attained level of maturity. The cycle can be repeated many times (see
Biological immortality Biological immortality (sometimes referred to as bio-indefinite mortality) is a state in which the rate of mortality from senescence is stable or decreasing, thus decoupling it from chronological age. Various unicellular and multicellular species, ...
). Larval morphology is highly varied amongst species, with well-developed and sclerotized heads, distinguishable thoracic and abdominal segments (usually the tenth, though sometimes the eighth or ninth). Beetle larvae can be differentiated from other insect larvae by their hardened, often darkened heads, the presence of chewing mouthparts, and
spiracle Spiracle or spiraculum may refer to: * Spiracle (arthropods), opening in the exoskeletons of some arthropods * Spiracle (vertebrates), openings on the surface of some vertebrates * Spiraculum, a genus of land snails in family Cyclophoridae Cycl ...
s along the sides of their bodies. Like adult beetles, the larvae are varied in appearance, particularly between beetle families. Beetles with somewhat flattened, highly mobile larvae include the ground beetles and rove beetles; their larvae are described as campodeiform. Some beetle larvae resemble hardened worms with dark head capsules and minute legs. These are elateriform larvae, and are found in the click beetle (Elateridae) and
darkling beetle Darkling beetle is the common name for members of the beetle family Tenebrionidae. The number of species in the Tenebrionidae is estimated at more than 20,000 and the family is cosmopolitan in distribution. Taxonomy ''Tenebrio'' is the Latin gen ...
(Tenebrionidae) families. Some elateriform larvae of click beetles are known as wireworms. Beetles in the Scarabaeoidea have short, thick larvae described as scarabaeiform, more commonly known as grubs. All beetle larvae go through several
instar An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ass ...
s, which are the developmental stages between each moult. In many species, the larvae simply increase in size with each successive instar as more food is consumed. In some cases, however, more dramatic changes occur. Among certain beetle families or genera, particularly those that exhibit parasitic lifestyles, the first instar (the planidium) is highly mobile to search out a host, while the following instars are more sedentary and remain on or within their host. This is known as
hypermetamorphosis Hypermetamorphosis, or heteromorphosis,P.J. Gullan & P.S. Cranston. 2010. The Insects: An Outline of Entomology, 4th Edition. Wiley-Blackwell. is a term used in entomology that refers to a class of variants of holometabolism, that is to say, com ...
; it occurs in the Meloidae,
Micromalthidae The telephone-pole beetle (''Micromalthus debilis'') is a beetle native to the eastern United States, and the only living representative of the otherwise extinct family Micromalthidae. They have an unusual lifecycle involving asexually reproducin ...
, and Ripiphoridae. The blister beetle '' Epicauta vittata'' (Meloidae), for example, has three distinct larval stages. Its first stage, the triungulin, has longer legs to go in search of the eggs of grasshoppers. After feeding for a week it moults to the second stage, called the caraboid stage, which resembles the larva of a carabid beetle. In another week it moults and assumes the appearance of a scarabaeid larva—the scarabaeidoid stage. Its penultimate larval stage is the pseudo-pupa or the coarcate larva, which will overwinter and pupate until the next spring. The larval period can vary widely. A fungus feeding staphylinid ''
Phanerota fasciata ''Phanerota fasciata'' is a species of rove beetle The rove beetles are a family (Staphylinidae) of beetles, primarily distinguished by their short elytra (wing covers) that typically leave more than half of their abdominal segments exposed. W ...
'' undergoes three moults in 3.2 days at room temperature while ''Anisotoma'' sp. (Leiodidae) completes its larval stage in the fruiting body of slime mold in 2 days and possibly represents the fastest growing beetles. Dermestid beetles, ''Trogoderma inclusum'' can remain in an extended larval state under unfavourable conditions, even reducing their size between moults. A larva is reported to have survived for 3.5 years in an enclosed container.


Pupa and adult

As with all endopterygotes, beetle larvae pupate, and from these
pupa A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...
e emerge fully formed, sexually mature adult beetles, or
imago In biology, the imago (Latin for "image") is the last stage an insect attains during its metamorphosis, its process of growth and development; it is also called the imaginal stage, the stage in which the insect attains maturity. It follows the f ...
s. Pupae never have mandibles (they are adecticous). In most pupae, the appendages are not attached to the body and are said to be
exarate A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...
; in a few beetles (Staphylinidae, Ptiliidae etc.) the appendages are fused with the body (termed as obtect pupae). Adults have extremely variable lifespans, from weeks to years, depending on the species. Some wood-boring beetles can have extremely long life-cycles. It is believed that when furniture or house timbers are infested by beetle larvae, the timber already contained the larvae when it was first sawn up. A
birch A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech-oak family Fagaceae. The genus ''Betula'' contains 30 ...
bookcase 40 years old released adult ''
Eburia quadrigeminata ''Eburia quadrigeminata'', the ivory-marked beetle or ivory-marked borer, is a species of beetle in the family Cerambycidae. Adult An adult is a human or other animal that has reached full growth. In human context, the term ''adult'' has mea ...
'' ( Cerambycidae), while ''
Buprestis aurulenta ''Buprestis aurulenta'', commonly known as the golden jewel beetle or golden buprestid, is a species of beetle in the genus '' Buprestis''. The larvae of ''Buprestis aurulenta'' live inside a variety of coniferous trees and can survive for long ...
'' and other
Buprestidae Buprestidae is a family of beetles known as jewel beetles or metallic wood-boring beetles because of their glossy iridescent colors. Larvae of this family are known as flatheaded borers. The family is among the largest of the beetles, with some ...
have been documented as emerging as much as 51 years after manufacture of wooden items.


Behaviour


Locomotion

The elytra allow beetles to both fly and move through confined spaces, doing so by folding the delicate wings under the elytra while not flying, and folding their wings out just before takeoff. The unfolding and folding of the wings is operated by muscles attached to the wing base; as long as the tension on the radial and cubital veins remains, the wings remain straight. Some beetle species (many Cetoniinae; some Scarabaeinae,
Curculionidae The Curculionidae are a family of weevils, commonly called snout beetles or true weevils. They are one of the largest animal families, with 6,800 genera and 83,000 species described worldwide. They are the sister group to the family Brentidae. T ...
and
Buprestidae Buprestidae is a family of beetles known as jewel beetles or metallic wood-boring beetles because of their glossy iridescent colors. Larvae of this family are known as flatheaded borers. The family is among the largest of the beetles, with some ...
) fly with the elytra closed, with the metathoracic wings extended under the lateral elytra margins. The altitude reached by beetles in flight varies. One study investigating the flight altitude of the ladybird species '' Coccinella septempunctata'' and '' Harmonia axyridis'' using radar showed that, whilst the majority in flight over a single location were at 150–195 m above ground level, some reached altitudes of over 1100 m. Many rove beetles have greatly reduced elytra, and while they are capable of flight, they most often move on the ground: their soft bodies and strong abdominal muscles make them flexible, easily able to wriggle into small cracks. Aquatic beetles use several techniques for retaining air beneath the water's surface. Diving beetles (Dytiscidae) hold air between the abdomen and the elytra when diving. Hydrophilidae have hairs on their under surface that retain a layer of air against their bodies. Adult crawling water beetles use both their elytra and their hind coxae (the basal segment of the back legs) in air retention, while whirligig beetles simply carry an air bubble down with them whenever they dive.


Communication

Beetles have a variety of ways to communicate, including the use of pheromones. The mountain pine beetle emits a pheromone to attract other beetles to a tree. The mass of beetles are able to overcome the chemical defenses of the tree. After the tree's defenses have been exhausted, the beetles emit an anti-aggregation pheromone. This species can
stridulate Stridulation is the act of producing sound by rubbing together certain body parts. This behavior is mostly associated with insects, but other animals are known to do this as well, such as a number of species of fish, snakes and spiders. The mech ...
to communicate, but others may use sound to defend themselves when attacked.


Parental care

Parental care is found in a few families of beetle, perhaps for protection against adverse conditions and predators. The rove beetle '' Bledius spectabilis'' lives in
salt marsh A salt marsh or saltmarsh, also known as a coastal salt marsh or a tidal marsh, is a coastal ecosystem in the upper coastal intertidal zone between land and open saltwater or brackish water that is regularly flooded by the tides. It is dominated ...
es, so the eggs and larvae are endangered by the rising
tide Tides are the rise and fall of sea levels caused by the combined effects of the gravity, gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide t ...
. The maternal beetle patrols the eggs and larvae, burrowing to keep them from flooding and asphyxiating, and protects them from the predatory carabid beetle ''
Dicheirotrichus gustavi '' Dicheirotrichus gustavi '' is a ground beetle which emerges from cracks or holes to feed on tidal salt marshes after dusk. Despite living in a coastal environment, it has no cycle of behaviour linked to the tides, simply scurrying for dry lan ...
'' and from the parasitoidal wasp ''
Barycnemis blediator ''Barycnemis blediator'' is a small parasitic wasp. It lays its eggs in the larvae of the salt marsh rove beetle, ''Bledius spectabilis ''Bledius spectabilis'', commonly known as the magnificent salt beetle, is a species of small rove beetl ...
'', which kills some 15% of the larvae. Burying beetles are attentive parents, and participate in cooperative care and feeding of their offspring. Both parents work to bury small animal carcass to serve as a food resource for their young and build a brood chamber around it. The parents prepare the carcass and protect it from competitors and from early decomposition. After their eggs hatch, the parents keep the larvae clean of fungus and bacteria and help the larvae feed by regurgitating food for them. Some
dung beetle Dung beetles are beetles that feed on feces. Some species of dung beetles can bury dung 250 times their own mass in one night. Many dung beetles, known as ''rollers'', roll dung into round balls, which are used as a food source or breeding cha ...
s provide parental care, collecting herbivore dung and laying eggs within that food supply, an instance of
mass provisioning Mass provisioning is a form of parental investment in which an adult insect, most commonly a hymenopteran such as a bee or wasp, stocks all the food for each of her offspring in a small chamber (a "cell") before she lays the egg. This behavior i ...
. Some species do not leave after this stage, but remain to safeguard their offspring. Most species of beetles do not display parental care behaviors after the eggs have been laid. Subsociality, where females guard their offspring, is well-documented in two families of Chrysomelidae, Cassidinae and Chrysomelinae.


Eusociality

Eusociality involves cooperative brood care (including brood care of offspring from other individuals), overlapping generations within a colony of adults, and a division of labor into reproductive and non-reproductive groups. Few organisms outside
Hymenoptera Hymenoptera is a large order (biology), order of insects, comprising the sawfly, sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are Par ...
exhibit this behavior; the only beetle to do so is the weevil '' Austroplatypus incompertus''. This
Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
n species lives in horizontal networks of tunnels, in the heartwood of ''
Eucalyptus ''Eucalyptus'' () is a genus of over seven hundred species of flowering trees, shrubs or mallees in the myrtle family, Myrtaceae. Along with several other genera in the tribe Eucalypteae, including '' Corymbia'', they are commonly known as euca ...
'' trees. It is one of more than 300 species of wood-boring
Ambrosia beetle Ambrosia beetles are beetles of the weevil subfamilies Scolytinae and Platypodinae ( Coleoptera, Curculionidae), which live in nutritional symbiosis with ambrosia fungi. The beetles excavate tunnels in dead, stressed, and healthy trees in wh ...
s which distribute the spores of ambrosia fungi. The fungi grow in the beetles' tunnels, providing food for the beetles and their larvae; female offspring remain in the tunnels and maintain the fungal growth, probably never reproducing. Cooperative brood care is also found in the bess beetles (
Passalidae Passalidae is a family of beetles known variously as "bessbugs", "bess beetles", "betsy beetles" or "horned passalus beetles". Nearly all of the 500-odd species are tropical; species found in North America are notable for their size, ranging from ...
) where the larvae feed on the semi-digested faeces of the adults.


Feeding

Beetles are able to exploit a wide diversity of food sources available in their many habitats. Some are
omnivore An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nutr ...
s, eating both plants and animals. Other beetles are highly specialized in their diet. Many species of leaf beetles, longhorn beetles, and weevils are very host-specific, feeding on only a single species of plant.
Ground beetle Ground beetles are a large, cosmopolitan distribution, cosmopolitan family (biology), family of beetles, the Carabidae, with more than 40,000 species worldwide, around 2,000 of which are found in North America and 2,700 in Europe. As of 2015, it i ...
s and
rove beetle The rove beetles are a family (Staphylinidae) of beetles, primarily distinguished by their short elytra (wing covers) that typically leave more than half of their abdominal segments exposed. With roughly 63,000 species in thousands of genera, the ...
s (
Staphylinidae The rove beetles are a family (Staphylinidae) of beetles, primarily distinguished by their short elytra (wing covers) that typically leave more than half of their abdominal segments exposed. With roughly 63,000 species in thousands of genera, the ...
), among others, are primarily carnivorous and catch and consume many other
arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...
s and small prey, such as earthworms and snails. While most predatory beetles are generalists, a few species have more specific prey requirements or preferences. In some species, digestive ability relies upon a
symbiotic Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...
relationship with
fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
- some beetles have yeasts living their guts, including some yeasts previously undiscovered anywhere else. Decaying organic matter is a primary diet for many species. This can range from dung, which is consumed by coprophagous species (such as certain
scarab beetle The family Scarabaeidae, as currently defined, consists of over 30,000 species of beetles worldwide; they are often called scarabs or scarab beetles. The classification of this family has undergone significant change in recent years. Several sub ...
s in the Scarabaeidae), to dead animals, which are eaten by
necrophagous Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feeding b ...
species (such as the carrion beetles,
Silphidae Silphidae is a family of beetles that are known commonly as large carrion beetles, carrion beetles or burying beetles. There are two subfamilies: Silphinae and Nicrophorinae. Nicrophorines are sometimes known as sexton beetles. The number of sp ...
). Some beetles found in dung and carrion are in fact predatory. These include members of the Histeridae and
Silphidae Silphidae is a family of beetles that are known commonly as large carrion beetles, carrion beetles or burying beetles. There are two subfamilies: Silphinae and Nicrophorinae. Nicrophorines are sometimes known as sexton beetles. The number of sp ...
, preying on the larvae of coprophagous and
necrophagous Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feeding b ...
insects. Many beetles feed under bark, some feed on wood while others feed on fungi growing on wood or leaf-litter. Some beetles have special
mycangia The term mycangium (pl., mycangia) is used in biology for special structures on the body of an animal that are adapted for the transport of symbiotic fungi (usually in spore form). This is seen in many xylophagous insects (e.g. horntails and bark b ...
, structures for the transport of fungal spores.


Ecology


Anti-predator adaptations

Beetles, both adults and larvae, are the prey of many animal
predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
s including mammals from
bat Bats are mammals of the order Chiroptera.''cheir'', "hand" and πτερόν''pteron'', "wing". With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most bi ...
s to
rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are na ...
s,
birds Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...
, lizards, amphibians, fishes, dragonflies, Asilidae, robberflies, Reduviidae, reduviid bugs, ants, other beetles, and spiders.#refEvans, Evans & Bellamy (2000), pp. 27–28 Beetles use a variety of anti-predator adaptations to defend themselves. These include
camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the ...
and mimicry against predators that hunt by sight, toxicity, and defensive behaviour.


Camouflage

Camouflage is common and widespread among beetle families, especially those that feed on wood or vegetation, such as leaf beetles (Chrysomelidae, which are often green) and weevils. In some species, sculpturing or various colored scales or hairs cause beetles such as the avocado weevil ''Heilipus apiatus'' to resemble bird dung or other inedible objects. Many beetles that live in sandy environments blend in with the coloration of that substrate.#refEvans, Evans & Bellamy (2000), p. 126


Mimicry and aposematism

Some
longhorn beetle The longhorn beetles (Cerambycidae), also known as long-horned or longicorns, are a large family of beetles, with over 35,000 species described. Most species are characterized by extremely long antennae, which are often as long as or longer than ...
s (Cerambycidae) are effective
Batesian mimics Batesian mimicry is a form of mimicry where a harmless species has evolved to imitate the warning signals of a harmful species directed at a predator of them both. It is named after the English naturalist Henry Walter Bates, after his work on Bu ...
of wasps. Beetles may combine coloration with behavioural mimicry, acting like the wasps they already closely resemble. Many other beetles, including Coccinellidae, ladybirds,
blister beetle Blister beetles are beetles of the family Meloidae, so called for their defensive secretion of a blistering agent, cantharidin. About 7,500 species are known worldwide. Many are conspicuous and some are aposematically colored, announcing their ...
s, and Lycidae, lycid beetles secrete distasteful or toxic substances to make them unpalatable or poisonous, and are often aposematic, where bright or contrasting animal coloration, coloration warn off predators; many beetles and other insects mimic these chemically protected species. Chemical defense is important in some species, usually being advertised by bright aposematic colors. Some Tenebrionidae use their posture for releasing noxious chemicals to warn off predators. Chemical defenses may serve purposes other than just protection from vertebrates, such as protection from a wide range of microbes. Some species sequester chemicals from the plants they feed on, incorporating them into their own defenses. Other species have special glands to produce deterrent chemicals. The defensive glands of carabid ground beetles produce a variety of hydrocarbons, aldehydes, phenols, quinones,
ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ar ...
s, and acids released from an opening at the end of the abdomen. African carabid beetles (for example, ''Anthia'') employ the same chemicals as ants: formic acid.#refEvans, Evans & Bellamy (2000) Bombardier beetles have well-developed pygidial glands that empty from the sides of the intersegment membranes between the seventh and eighth abdominal segments. The gland is made of two containing chambers, one for hydroquinones and hydrogen peroxide, the other holding hydrogen peroxide and catalase enzymes. These chemicals mix and result in an explosive ejection, reaching a temperature of around , with the breakdown of hydroquinone to hydrogen, oxygen, and quinone. The oxygen propels the noxious chemical spray as a jet that can be aimed accurately at predators.


Other defenses

Large ground-dwelling beetles such as Carabidae, the rhinoceros beetle and the longhorn beetles defend themselves using strong Mandible (insect), mandibles, or heavily sclerotised (armored) spines or horns to deter or fight off predators. Many species of weevil that feed out in the open on leaves of plants react to attack by employing a drop-off reflex. Some combine it with thanatosis, in which they close up their appendages and "play dead". McHugh (2009), p. 199 The click beetles ( Elateridae) can suddenly catapult themselves out of danger by releasing the energy stored by a click mechanism, which consists of a stout spine on the prosternum and a matching groove in the mesosternum. Some species startle an attacker by producing sounds through a process known as stridulation.


Parasitism

A few species of beetles are Parasitism#Types, ectoparasitic on mammals. One such species, ''Platypsyllus castoris'', parasitises beavers (Beaver, ''Castor'' spp.). This beetle lives as a parasite both as a larva and as an adult, feeding on epidermal tissue and possibly on skin secretions and wound exudates. They are strikingly flattened dorsoventrally, no doubt as an adaptation for slipping between the beavers' hairs. They are wingless and eyeless, as are many other ectoparasites. Others are kleptoparasites of other invertebrates, such as the small hive beetle (''Aethina tumida'') that infests honey bee nests, while many species are parasitic inquilines or myrmecophily in Staphylinidae, commensal in the nests of ants. A few groups of beetles are primary parasitoids of other insects, feeding off of, and eventually killing their hosts.


Pollination

Beetle-pollinated flowers are usually large, greenish or off-white in color, and heavily scented. Scents may be spicy, fruity, or similar to decaying organic material. Beetles were most likely the first insects to pollinate flowers. Most beetle-pollinated flowers are flattened or dish-shaped, with pollen easily accessible, although they may include Pollination trap, traps to keep the beetle longer. The plants' ovaries are usually well protected from the biting mouthparts of their pollinators. The beetle families that habitually pollinate flowers are the
Buprestidae Buprestidae is a family of beetles known as jewel beetles or metallic wood-boring beetles because of their glossy iridescent colors. Larvae of this family are known as flatheaded borers. The family is among the largest of the beetles, with some ...
,
Cantharidae The soldier beetles (Cantharidae) are relatively soft-bodied, straight-sided beetles. They are cosmopolitan in distribution. One of the first described species has a color pattern reminiscent of the Red coat (British army), red coats of early Bri ...
, Cerambycidae, Cleridae, Dermestidae, Lycidae, Melyridae,
Mordellidae The Mordellidae are a family of beetles commonly known as tumbling flower beetles for the typical irregular movements they make when escaping predators, or as pintail beetles due to their abdominal tip which aids them in performing these tumbling ...
, Sap beetle, Nitidulidae and Scarabaeidae. Beetles may be particularly important in some parts of the world such as semiarid areas of southern Africa and southern California and the montane grasslands of KwaZulu-Natal in South Africa.


Mutualism

Mutualism (biology), Mutualism is well known in a few beetles, such as the ambrosia beetle, which partners with fungi to digest the wood of dead trees. The beetles excavate tunnels in dead trees in which they cultivate fungal gardens, their sole source of nutrition. After landing on a suitable tree, an ambrosia beetle excavates a tunnel in which it releases spores of its fungal symbiont. The fungus penetrates the plant's xylem tissue, digests it, and concentrates the nutrients on and near the surface of the beetle gallery, so the weevils and the fungus both benefit. The beetles cannot eat the wood due to toxins, and uses its relationship with fungi to help overcome the defenses of its host tree in order to provide nutrition for their larvae. Chemically mediated by a bacterially produced polyunsaturated peroxide, this mutualistic relationship between the beetle and the fungus is coevolved.


Tolerance of extreme environments

About 90% of beetle species enter a period of adult diapause, a quiet phase with reduced metabolism to tide unfavourable environmental conditions. Adult diapause is the most common form of diapause in Coleoptera. To endure the period without food (often lasting many months) adults prepare by accumulating reserves of lipids, glycogen, proteins and other substances needed for resistance to future hazardous changes of environmental conditions. This diapause is induced by signals heralding the arrival of the unfavourable season; usually the cue is photoperiodic. Short (decreasing) day length serves as a signal of approaching winter and induces winter diapause (hibernation). A study of hibernation in the Arctic beetle ''Pterostichus brevicornis'' showed that the body fat levels of adults were highest in autumn with the alimentary canal filled with food, but empty by the end of January. This loss of body fat was a gradual process, occurring in combination with dehydration. All insects are poikilothermic, so the ability of a few beetles to live in extreme environments depends on their resilience to unusually high or low temperatures. The bark beetle ''Pityogenes chalcographus'' can survive whilst overwintering beneath tree bark; the Alaskan beetle ''Cucujus clavipes puniceus'' is able to withstand ; its larvae may survive . At these low temperatures, the formation of ice crystals in internal fluids is the biggest threat to survival to beetles, but this is prevented through the production of antifreeze proteins that stop water molecules from grouping together. The low temperatures experienced by ''Cucujus clavipes'' can be survived through their deliberate dehydration in conjunction with the antifreeze proteins. This concentrates the antifreezes several fold. The
hemolymph Hemolymph, or haemolymph, is a fluid, analogous to the blood in vertebrates, that circulates in the interior of the arthropod (invertebrate) body, remaining in direct contact with the animal's tissues. It is composed of a fluid plasma in which ...
of the mealworm beetle ''Tenebrio molitor'' contains several antifreeze proteins. The Alaskan beetle ''Upis ceramboides'' can survive −60 °C: its cryoprotectants are xylomannan, a molecule consisting of a sugar bound to a fatty acid, and the sugar-alcohol, threitol. Conversely, desert dwelling beetles are adapted to tolerate high temperatures. For example, the Tenebrionidae, Tenebrionid beetle ''Onymacris rugatipennis'' can withstand . Tiger beetles in hot, sandy areas are often whitish (for example, ''Habroscelimorpha dorsalis''), to reflect more heat than a darker color would. These beetles also exhibits behavioural adaptions to tolerate the heat: they are able to stand erect on their tarsi to hold their bodies away from the hot ground, seek shade, and turn to face the sun so that only the front parts of their heads are directly exposed. The fogstand beetle of the Namib Desert, ''Stenocara gracilipes'', is able to fog collection, collect water from fog, as its elytra have a textured surface combining Hydrophile, hydrophilic (water-loving) bumps and waxy,
hydrophobic In chemistry, hydrophobicity is the physical property of a molecule that is seemingly repelled from a mass of water (known as a hydrophobe). In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, th ...
troughs. The beetle faces the early morning breeze, holding up its abdomen; droplets condense on the elytra and run along ridges towards their mouthparts. Similar adaptations are found in several other Namib desert beetles such as ''Onymacris unguicularis''. Some terrestrial beetles that exploit shoreline and floodplain habitats have physiological adaptations for surviving floods. In the event of flooding, adult beetles may be mobile enough to move away from flooding, but larvae and pupa often cannot. Adults of ''Cicindela togata'' are unable to survive immersion in water, but larvae are able to survive a prolonged period, up to 6 days, of Hypoxia (environmental), anoxia during floods. Anoxia tolerance in the larvae may have been sustained by switching to anaerobic metabolic pathways or by reducing metabolic rate. Anoxia tolerance in the adult carabid beetle ''Pelophilia borealis'' was tested in laboratory conditions and it was found that they could survive a continuous period of up to 127 days in an atmosphere of 99.9% nitrogen at 0 °C.


Migration

Many beetle species undertake annual mass movements which are termed as migrations. These include the pollen beetle ''Meligethes aeneus'' and many species of Coccinellidae, coccinellids. These mass movements may also be opportunistic, in search of food, rather than seasonal. A 2008 study of an unusually large outbreak of Mountain Pine Beetle (''Dendroctonus ponderosae'') in British Columbia found that beetles were capable of flying 30–110 km per day in densities of up to 18,600 beetles per hectare.


Relationship to humans


In ancient cultures

Several species of dung beetle, especially the sacred scarab, ''Scarabaeus sacer'', were revered in Ancient Egypt. The hieroglyphic image of the beetle may have had existential, fictional, or ontologic significance. Images of the scarab in bone, ivory, stone, Egyptian faience, and precious metals are known from the Sixth Dynasty and up to the period of Roman rule. The scarab was of prime significance in the funerary cult of ancient Egypt. The scarab was linked to Khepri, the god of the rising sun, from the supposed resemblance of the rolling of the dung ball by the beetle to the rolling of the sun by the god. Some of ancient Egypt's neighbors adopted the scarab motif for scaraboid seal, seals of varying types. The best-known of these are the Judean LMLK seals, where eight of 21 designs contained scarab beetles, which were used exclusively to stamp impressions on storage jars during the reign of Hezekiah. Beetles are mentioned as a symbol of the sun, as in ancient Egypt, in Plutarch's 1st century ''Moralia''. The Greek Magical Papyri of the 2nd century BC to the 5th century AD describe scarabs as an ingredient in a spell. Pliny the Elder discusses beetles in his ''Natural History (Pliny), Natural History'', describing the Lucanus cervus, stag beetle: "Some insects, for the preservation of their wings, are covered with (elytra)—the beetle, for instance, the wing of which is peculiarly fine and frail. To these insects a sting has been denied by Nature; but in one large kind we find horns of a remarkable length, two-pronged at the extremities, and forming pincers, which the animal closes when it is its intention to bite." The stag beetle is recorded in a Greek myth by Nicander and recalled by Antoninus Liberalis in which Cerambus is turned into a beetle: "He can be seen on trunks and has hook-teeth, ever moving his jaws together. He is black, long and has hard wings like a great dung beetle". The story concludes with the comment that the beetles were used as toys by young boys, and that the head was removed and worn as a pendant.


As pests

About 75% of beetle species are phytophagous in both the larval and adult stages. Many feed on economically important plants and stored plant products, including trees, cereals, tobacco, and dried fruits. Some, such as the boll weevil, which feeds on cotton buds and flowers, can cause extremely serious damage to agriculture. The boll weevil crossed the Rio Grande near Brownsville, Texas, Brownsville, Texas, to enter the United States from Mexico around 1892, and had reached southeastern Alabama by 1915. By the mid-1920s, it had entered all cotton-growing regions in the US, traveling per year. It remains the most destructive cotton pest in North America. Mississippi State University has estimated, since the boll weevil entered the United States, it has cost cotton producers about $13 billion, and in recent times about $300 million per year. The bark beetle, elm leaf beetle and the Asian longhorned beetle (''Anoplophora glabripennis'') are among the species that attack elm trees. Bark beetles (Scolytidae) carry Dutch elm disease as they move from infected breeding sites to healthy trees. The disease has devastated elm trees across Europe and North America. Some species of beetle have evolved immunity to insecticides. For example, the Colorado potato beetle, ''Leptinotarsa decemlineata'', is a destructive pest of potato plants. Its hosts include other members of the Solanaceae, such as nightshade, tomato, eggplant and capsicum, as well as the potato. Different populations have between them developed resistance to all major classes of insecticide. The Colorado potato beetle was evaluated as a tool of entomological warfare during World War II, the idea being to use the beetle and its larvae to damage the crops of enemy nations. Germany tested its Colorado potato beetle weaponisation program south of Frankfurt, Germany, Frankfurt, releasing 54,000 beetles. The death watch beetle, ''Xestobium rufovillosum'' (Ptinidae), is a serious pest of older wooden buildings in Europe. It attacks hardwoods such as oak and chestnut, always where some fungal decay has taken or is taking place. The actual introduction of the pest into buildings is thought to take place at the time of construction. Other pests include the coconut hispine beetle, ''Brontispa longissima'', which feeds on young leaves, seedlings and mature coconut trees, causing serious economic damage in the Philippines. The mountain pine beetle is a destructive pest of mature or weakened lodgepole pine, sometimes affecting large areas of Canada.


As beneficial resources

Beetles can be beneficial to human economics by controlling the populations of pests. The larvae and adults of some species of
lady beetle Coccinellidae () is a widespread family of small beetles ranging in size from . They are commonly known as ladybugs in North America and ladybirds in Great Britain. Some entomologists prefer the names ladybird beetles or lady beetles as they ...
s (
Coccinellidae Coccinellidae () is a widespread family of small beetles ranging in size from . They are commonly known as ladybugs in North America and ladybirds in Great Britain. Some entomologists prefer the names ladybird beetles or lady beetles as they ...
) feed on aphids that are pests. Other lady beetles feed on
scale insect Scale insects are small insects of the order Hemiptera, suborder Sternorrhyncha. Of dramatically variable appearance and extreme sexual dimorphism, they comprise the infraorder Coccomorpha which is considered a more convenient grouping than the ...
s, whitefly and mealybugs. If normal food sources are scarce, they may feed on small caterpillars, young plant bugs, or honeydew (secretion), honeydew and nectar.
Ground beetle Ground beetles are a large, cosmopolitan distribution, cosmopolitan family (biology), family of beetles, the Carabidae, with more than 40,000 species worldwide, around 2,000 of which are found in North America and 2,700 in Europe. As of 2015, it i ...
s (Carabidae) are common
predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
s of many insect pests, including fly eggs, caterpillars, and wireworms. Ground beetles can help to control weeds by eating their seeds in the soil, reducing the need for herbicides to protect crops. The effectiveness of some species in reducing certain plant populations has resulted in the deliberate introduction of beetles in order to control weeds. For example, the genus ''Zygogramma'' is native to North America but has been used to control ''Parthenium hysterophorus'' in India and ''Ambrosia artemisiifolia'' in Russia. Dung beetles (Scarabidae) have been successfully used to reduce the populations of pestilent flies, such as ''Musca vetustissima'' and ''Haematobia exigua'' which are serious pests of cattle in
Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
. The beetles make the dung unavailable to breeding pests by quickly rolling and burying it in the soil, with the added effect of improving soil fertility, tilth, and nutrient cycling. The Australian Dung Beetle Project (1965–1985), introduced species of dung beetle to Australia from South Africa and Europe to reduce populations of ''Musca vetustissima'', following successful trials of this technique in Hawaii. The American Institute of Biological Sciences reports that dung beetles save the United States cattle industry an estimated US$380 million annually through burying above-ground livestock feces. The Dermestidae are often used in taxidermy and in the preparation of scientific specimens, to clean soft tissue from bones. Larvae feed on and remove cartilage along with other soft tissue.


As food and medicine

Beetles are the most widely eaten insects, with about 344 species used as food, usually at the larval stage. The mealworm (the larva of the
darkling beetle Darkling beetle is the common name for members of the beetle family Tenebrionidae. The number of species in the Tenebrionidae is estimated at more than 20,000 and the family is cosmopolitan in distribution. Taxonomy ''Tenebrio'' is the Latin gen ...
) and the rhinoceros beetle are among the species commonly eaten. A wide range of species is also used in folk medicine to treat those suffering from a variety of disorders and illnesses, though this is done without clinical studies supporting the efficacy of such treatments.


As biodiversity indicators

Due to their habitat specificity, many species of beetles have been suggested as suitable as indicators, their presence, numbers, or absence providing a measure of habitat quality. Predatory beetles such as the tiger beetles (Cicindelidae) have found scientific use as an indicator taxon for measuring regional patterns of biodiversity. They are suitable for this as their taxonomy is stable; their life history is well described; they are large and simple to observe when visiting a site; they occur around the world in many habitats, with species specialised to particular habitats; and their occurrence by species accurately indicates other species, both vertebrate and invertebrate. According to the habitats, many other groups such as the rove beetles in human-modified habitats, dung beetles in savannas and saproxylic beetles in forests have been suggested as potential indicator species.


In art and adornment

Many beetles have durable elytra that has been used as material in art, with beetlewing the best example. Sometimes, they are incorporated into ritual objects for their religious significance. Whole beetles, either as-is or encased in clear plastic, are made into objects ranging from cheap souvenirs such as key chains to expensive fine-art jewellery. In parts of Mexico, beetles of the genus ''Zopherus'' are made into living brooches by attaching costume jewelry and golden chains, which is made possible by the incredibly hard elytra and sedentary habits of the genus.


In entertainment

Fighting beetles are used insect fighting, for entertainment and gambling. This sport exploits the territorial behavior and mating competition of certain species of large beetles. In the Chiang Mai district of northern Thailand, male ''Xylotrupes'' rhinoceros beetles are caught in the wild and trained for fighting. Females are held inside a log to stimulate the fighting males with their pheromones. These fights may be competitive and involve gambling both money and property. In South Korea the Dytiscidae species ''Cybister tripunctatus'' is used in a roulette-like game. Beetles are sometimes used as instruments: the Onabasulu of Papua New Guinea historically used the "Hugu (instrument), ''hugu''" weevil ''Rhynchophorus ferrugineus'' as a musical instrument by letting the human mouth serve as a variable resonance chamber for the wing vibrations of the live adult beetle.


As pets

Some species of beetle are kept as pets, for example diving beetles ( Dytiscidae) may be kept in a domestic fresh water tank. In Japan the practice of keeping horned rhinoceros beetles ( Dynastinae) and stag beetles (Stag beetle, Lucanidae) is particularly popular amongst young boys. Such is the popularity in Japan that vending machines dispensing live beetles were developed in 1999, each holding up to 100 stag beetles.


As things to collect

Beetle collecting became extremely popular in the Victorian era. The naturalist Alfred Russel Wallace collected (by his own count) a total of 83,200 beetles during the eight years described in his 1869 book ''The Malay Archipelago'', including 2,000 species new to science.


As inspiration for technologies

Several coleopteran adaptations have attracted interest in biomimetics with possible commercial applications. The bombardier beetle's powerful repellent spray has inspired the development of a fine mist spray technology, claimed to have a low carbon impact compared to aerosol sprays. Moisture harvesting behavior by the Namib desert beetle (''Stenocara gracilipes'') has inspired a self-filling water bottle which utilises hydrophilic and hydrophobic materials to benefit people living in dry regions with no regular rainfall. Living beetles have been used as cyborgs. A Defense Advanced Research Projects Agency funded project implanted electrodes into ''Mecynorhina torquata'' beetles, allowing them to be remotely controlled via a radio receiver held on its back, as proof-of-concept for surveillance work. Similar technology has been applied to enable a human operator to control the free-flight steering and walking gaits of ''Mecynorhina torquata'' as well as graded turning and backward walking of ''Zophobas morio''. Research published in 2020 sought to create a robotic camera backpack for beetles. Miniature cameras weighing 248 mg were attached to live beetles of the Tenebrionidae, Tenebrionid genera ''Asbolus (beetle), Asbolus'' and ''Eleodes''. The cameras filmed over a 60° range for up to 6 hours.


In conservation

Since beetles form such a large part of the world's biodiversity, their conservation is important, and equally, loss of habitat and biodiversity is essentially certain to impact on beetles. Many species of beetles have very specific habitats and long life cycles that make them vulnerable. Some species are highly threatened while others are already feared extinct. Island species tend to be more susceptible as in the case of ''Helictopleurus undatus'' of Madagascar which is thought to have gone extinct during the late 20th century. Conservationists have attempted to arouse a liking for beetles with flagship species like the stag beetle, ''Lucanus cervus'', and tiger beetles (Cicindelidae). In Japan the Genji firefly, ''Luciola cruciata'', is extremely popular, and in South Africa the Addo elephant dung beetle offers promise for broadening ecotourism beyond the big five game, big five tourist mammal species. Popular dislike of pest beetles, too, can be turned into public interest in insects, as can unusual ecological adaptations of species like the fairy shrimp hunting beetle, ''Cicinis bruchi''.


Notes


References


Bibliography

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Further reading

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External links


Coleoptera
from the Tree of Life Web Project *
''Käfer der Welt''

Coleoptera Atlas

Beetles – Coleoptera
{{Authority control Beetles, Extant Pennsylvanian first appearances Insects in culture