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Butterflies are insects in the macrolepidopteran
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, ...
Rhopalocera from 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 ...
Lepidoptera Lepidoptera ( ) is an order (biology), order of insects that includes butterfly, butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 Family (biology), families and 46 Taxonomic r ...
, which also includes moths. Adult butterflies have large, often brightly coloured wings, and conspicuous, fluttering flight. The group comprises the large
superfamily SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid sequences into known structural domains, especially into SCOP superfamilies. Domains are functional, str ...
Papilionoidea, which contains at least one former group, the skippers (formerly the superfamily "Hesperioidea"), and the most recent analyses suggest it also contains the moth-butterflies (formerly the superfamily "Hedyloidea"). Butterfly fossils date to the Paleocene, about 56 million years ago. Butterflies have a four-stage life cycle, as like most insects they undergo complete metamorphosis. Winged adults lay eggs on the food plant on which their larvae, known as
caterpillar Caterpillars ( ) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths). As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder Sym ...
s, will feed. The caterpillars grow, sometimes very rapidly, and when fully developed, pupate in a
chrysalis 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 ...
. When
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 ...
is complete, the pupal skin splits, the adult insect climbs out, and after its wings have expanded and dried, it flies off. Some butterflies, especially in the tropics, have several generations in a year, while others have a single generation, and a few in cold locations may take several years to pass through their entire life cycle. Butterflies are often polymorphic, and many species make use of camouflage,
mimicry In evolutionary biology, mimicry is an evolved resemblance between an organism and another object, often an organism of another species. Mimicry may evolve between different species, or between individuals of the same species. Often, mimicry f ...
, and
aposematism Aposematism is the advertising by an animal to potential predators that it is not worth attacking or eating. This unprofitability may consist of any defences which make the prey difficult to kill and eat, such as toxicity, venom, foul taste or ...
to evade their predators. Some, like the monarch and the painted lady,
migrate Migration, migratory, or migrate may refer to: Human migration * Human migration, physical movement by humans from one region to another ** International migration, when peoples cross state boundaries and stay in the host state for some minimum le ...
over long distances. Many butterflies are attacked by parasites or
parasitoid In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...
s, including wasps,
protozoa Protozoa (singular: protozoan or protozoon; alternative plural: protozoans) are a group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic tissues and debris. Histo ...
ns, flies, and other invertebrates, or are preyed upon by other organisms. Some species are pests because in their larval stages they can damage domestic crops or trees; other species are agents of pollination of some plants. Larvae of a few butterflies (e.g.,
harvesters Harvester may refer to: Agriculture and forestry * Combine harvester, a machine commonly used to harvest grain crops * Forage harvester, a machine used to harvest forage * Harvester (forestry), a type of heavy vehicle employed in cut-to-length lo ...
) eat harmful insects, and a few are predators of ants, while others live as mutualists in association with ants. Culturally, butterflies are a popular motif in the visual and literary arts. The Smithsonian Institution says "butterflies are certainly one of the most appealing creatures in nature".


Etymology

The '' Oxford English Dictionary'' derives the word straightforwardly from
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 ...
''butorflēoge'', butter-fly; similar names in Old Dutch and Old High German show that the name is ancient, but modern Dutch and German use different words (''vlinder'' and ''Schmetterling'') and the common name often varies substantially between otherwise closely-related languages. A possible source of the name is the bright yellow male of the brimstone ('' Gonepteryx rhamni''); another is that butterflies were on the wing in meadows during the spring and summer butter season while the grass was growing.


Paleontology

The earliest
Lepidoptera Lepidoptera ( ) is an order (biology), order of insects that includes butterfly, butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 Family (biology), families and 46 Taxonomic r ...
fossils date to the Triassic- Jurassic boundary, around 200 million years ago. Butterflies evolved from moths, so while the butterflies are
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 ...
(forming a single
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 moths are not. The oldest known butterfly is '' Protocoeliades kristenseni'' from the
Palaeocene The Paleocene, ( ) or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek ''palai ...
aged Fur Formation of Denmark, approximately 55 million years old, which belongs to the family
Hesperiidae Skippers are a family of the Lepidoptera (moths and butterflies) named the Hesperiidae. Being diurnal, they are generally called butterflies. They were previously placed in a separate superfamily, Hesperioidea; however, the most recent taxonomy ...
(skippers). Molecular clock estimates suggest that butterflies originated sometime in the mid- Cretaceous, but only significantly diversified during the Cenozoic. The oldest American butterfly is the Late Eocene '' Prodryas persephone'' from the
Florissant Fossil Beds The Florissant Formation is a sedimentary geologic formation outcropping around Florissant, Teller County, Colorado. The formation is noted for the abundant and exceptionally preserved insect and plant fossils that are found in the mudstones and ...
, approximately 34 million years old. File:Prodryas.png, '' Prodryas persephone'', a Late Eocene butterfly from the
Florissant Fossil Beds The Florissant Formation is a sedimentary geologic formation outcropping around Florissant, Teller County, Colorado. The formation is noted for the abundant and exceptionally preserved insect and plant fossils that are found in the mudstones and ...
, 1887 engraving File:PZSL1889Plate31 Fossil Papilionid Butterfly Lithopsyche antiqua from Early Oligocene Bembridge Marls.png, '' Lithopsyche antiqua'', an Early Oligocene butterfly from the Bembridge Marls, Isle of Wight, 1889 engraving


Taxonomy and phylogeny

Traditionally, butterflies have been divided into the
superfamily SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid sequences into known structural domains, especially into SCOP superfamilies. Domains are functional, str ...
Papilionoidea excluding the smaller groups of the
Hesperiidae Skippers are a family of the Lepidoptera (moths and butterflies) named the Hesperiidae. Being diurnal, they are generally called butterflies. They were previously placed in a separate superfamily, Hesperioidea; however, the most recent taxonomy ...
(skippers) and the more moth-like Hedylidae of America. Phylogenetic analysis suggests that the traditional Papilionoidea is
paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...
with respect to the other two groups, so they should both be included within Papilionoidea, to form a single butterfly group, thereby synonymous with the clade Rhopalocera.


Biology


General description

Butterfly adults are characterized by their four scale-covered wings, which give the Lepidoptera their name ( Ancient Greek λεπίς lepís, scale + πτερόν pterón, wing). These scales give butterfly wings their colour: they are pigmented with melanins that give them blacks and browns, as well as uric acid derivatives and flavones that give them yellows, but many of the blues, greens, reds and iridescent colours are created by structural coloration produced by the micro-structures of the scales and hairs. As in all insects, the body is divided into three sections: the head, thorax, and abdomen. The thorax is composed of three segments, each with a pair of legs. In most families of butterfly the antennae are clubbed, unlike those of moths which may be threadlike or feathery. The long proboscis can be coiled when not in use for sipping nectar from flowers. Nearly all butterflies are diurnal, have relatively bright colours, and hold their wings vertically above their bodies when at rest, unlike the majority of moths which fly by night, are often cryptically coloured (well camouflaged), and either hold their wings flat (touching the surface on which the moth is standing) or fold them closely over their bodies. Some day-flying moths, such as the hummingbird hawk-moth, are exceptions to these rules. Butterfly larvae,
caterpillar Caterpillars ( ) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths). As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder Sym ...
s, have a hard (
sclerotised Sclerotin is a component of the cuticle of various Arthropoda, most familiarly insects. It is formed by cross-linking members of particular classes of protein molecules, a biochemical process called sclerotization, a form of tanning in which qui ...
) head with strong mandibles used for cutting their food, most often leaves. They have cylindrical bodies, with ten segments to the abdomen, generally with short prolegs on segments 3–6 and 10; the three pairs of true legs on the thorax have five segments each. Many are well camouflaged; others are aposematic with bright colours and bristly projections containing toxic chemicals obtained from their food plants. The pupa or chrysalis, unlike that of moths, is not wrapped in a cocoon. Many butterflies are sexually dimorphic. Most butterflies have the ZW sex-determination system where females are the heterogametic sex (ZW) and males homogametic (ZZ).


Distribution and migration

Butterflies are distributed worldwide except Antarctica, totalling some 18,500 species. Of these, 775 are Nearctic; 7,700 Neotropical; 1,575
Palearctic The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa. The realm consists of several bioregions: the Euro-Sibe ...
; 3,650
Afrotropical The Afrotropical realm is one of Earth's eight biogeographic realms. It includes Africa south of the Sahara Desert, the majority of the Arabian Peninsula, the island of Madagascar, southern Iran and extreme southwestern Pakistan, and the island ...
; and 4,800 are distributed across the combined
Oriental The Orient is a term for the East in relation to Europe, traditionally comprising anything belonging to the Eastern world. It is the antonym of ''Occident'', the Western World. In English, it is largely a metonym for, and coterminous with, the ...
and Australian/ Oceania regions. The
monarch butterfly The monarch butterfly or simply monarch (''Danaus plexippus'') is a milkweed butterfly (subfamily Danainae) in the family Nymphalidae. Other common names, depending on region, include milkweed, common tiger, wanderer, and black-veined brown. It ...
is native to the Americas, but in the nineteenth century or before, spread across the world, and is now found in Australia, New Zealand, other parts of Oceania, and the Iberian Peninsula. It is not clear how it dispersed; adults may have been blown by the wind or larvae or pupae may have been accidentally transported by humans, but the presence of suitable host plants in their new environment was a necessity for their successful establishment. Many butterflies, such as the painted lady, monarch, and several danaine migrate for long distances. These migrations take place over a number of generations and no single individual completes the whole trip. The eastern North American population of monarchs can travel thousands of miles south-west to overwintering sites in Mexico. There is a reverse migration in the spring. It has recently been shown that the British painted lady undertakes a 9,000-mile round trip in a series of steps by up to six successive generations, from tropical Africa to the Arctic Circle — almost double the length of the famous migrations undertaken by monarch. Spectacular large-scale migrations associated with the monsoon are seen in peninsular India. Migrations have been studied in more recent times using wing tags and also using stable hydrogen isotopes. Butterflies navigate using a time-compensated sun compass. They can see polarized light and therefore orient even in cloudy conditions. The polarized light near the ultraviolet spectrum appears to be particularly important. Many migratory butterflies live in semi-arid areas where breeding seasons are short. The life histories of their host plants also influence butterfly behaviour.


Life cycle

Butterflies in their adult stage can live from a week to nearly a year depending on the species. Many species have long larval life stages while others can remain
dormant Dormant, "sleeping", may refer to: Science *Dormancy Dormancy is a period in an organism's life cycle when growth, development, and (in animals) physical activity are temporarily stopped. This minimizes metabolic activity and therefore helps ...
in their pupal or egg stages and thereby survive winters. The
Melissa Arctic ''Oeneis melissa'', the Melissa Arctic, is a species of butterfly in the family Nymphalidae. The wingspan is 42–51 mm. The larvae feed on various sedges, including ''Carex bigelowii'' and ''Carex rupestris''. Subspecies *''Oeneis melis ...
(''Oeneis melissa'') overwinters twice as a caterpillar. Butterflies may have one or more broods per year. The number of generations per year varies from temperate to tropical regions with tropical regions showing a trend towards multivoltinism. Courtship is often aerial and often involves pheromones. Butterflies then land on the ground or on a perch to mate. Copulation takes place tail-to-tail and may last from minutes to hours. Simple photoreceptor cells located at the genitals are important for this and other adult behaviours. The male passes a spermatophore to the female; to reduce sperm competition, he may cover her with his scent, or in some species such as the Apollos ('' Parnassius'') plugs her genital opening to prevent her from mating again. The vast majority of butterflies have a four-stage life cycle;
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 ...
, larva (caterpillar), pupa (chrysalis) and imago (adult). In the genera '' Colias'', '' Erebia'', '' Euchloe'', and ''Parnassius'', a small number of species are known that reproduce semi-parthenogenetically; when the female dies, a partially developed larva emerges from her abdomen.


Egg

Butterfly eggs are protected by a hard-ridged outer layer of shell, called the ''chorion''. This is lined with a thin coating of wax which prevents the egg from drying out before the larva has had time to fully develop. Each egg contains a number of tiny funnel-shaped openings at one end, called ''micropyles''; the purpose of these holes is to allow sperm to enter and fertilize the egg. Butterfly eggs vary greatly in size and shape between species, but are usually upright and finely sculptured. Some species lay eggs singly, others in batches. Many females produce between one hundred and two hundred eggs. Butterfly eggs are fixed to a leaf with a special glue which hardens rapidly. As it hardens it contracts, deforming the shape of the egg. This glue is easily seen surrounding the base of every egg forming a meniscus. The nature of the glue has been little researched but in the case of '' Pieris brassicae'', it begins as a pale yellow granular secretion containing acidophilic proteins. This is viscous and darkens when exposed to air, becoming a water-insoluble, rubbery material which soon sets solid. Butterflies in the genus '' Agathymus'' do not fix their eggs to a leaf, instead the newly laid eggs fall to the base of the plant. Eggs are almost invariably laid on plants. Each species of butterfly has its own host plant range and while some species of butterfly are restricted to just one species of plant, others use a range of plant species, often including members of a common family. In some species, such as the great spangled fritillary, the eggs are deposited close to but not on the food plant. This most likely happens when the egg overwinters before hatching and where the host plant loses its leaves in winter, as do violets in this example. The egg stage lasts a few weeks in most butterflies, but eggs laid close to winter, especially in temperate regions, go through a diapause (resting) stage, and the hatching may take place only in spring. Some temperate region butterflies, such as the
Camberwell beauty ''Nymphalis antiopa'', known as the mourning cloak in North America and the Camberwell beauty in Britain, is a large butterfly native to Eurasia and North America. The immature form of this species is sometimes known as the spiny elm caterpillar ...
, lay their eggs in the spring and have them hatch in the summer.


Caterpillar larva

Butterfly larvae, or caterpillars, consume plant leaves and spend practically all of their time searching for and eating food. Although most caterpillars are herbivorous, a few species are predators: ''
Spalgis epius ''Spalgis epius'', the apefly, is a small butterfly found in the Indomalayan realm that belongs to the lycaenids or blues family. It gets its name from the supposed resemblance of its pupa to the face of an ape. Description Male Upperside: du ...
'' eats
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, while lycaenids such as '' Liphyra brassolis'' are myrmecophilous, eating ant larvae. Some larvae, especially those of the Lycaenidae, form mutual associations with ants. They communicate with the ants using vibrations that are transmitted through the
substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (locomotion), the surface over which an organism lo ...
as well as using chemical signals. The ants provide some degree of protection to these larvae and they in turn gather honeydew secretions. Large blue (''Phengaris arion'') caterpillars trick ''
Myrmica ''Myrmica'' is a genus of ants within the subfamily Myrmicinae. It is widespread throughout the temperate regions of the Holarctic and high mountains in Southeast Asia. The genus consists of around 200 known species and additional subspecies, ...
'' ants into taking them back to the
ant colony An ant colony is a population of a single ant species capable to maintain its complete lifecycle. Ant colonies are eusocial, communal, and efficiently organized and are very much like those found in other social Hymenoptera, though the vario ...
where they feed on the ant eggs and larvae in a parasitic relationship. Caterpillars mature through a series of developmental stages known as instars. Near the end of each stage, the larva undergoes a process called apolysis, mediated by the release of a series of neurohormones. During this phase, the
cuticle A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non- homologous, differing in their origin, structu ...
, a tough outer layer made of a mixture of
chitin Chitin ( C8 H13 O5 N)n ( ) is a long-chain polymer of ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is probably the second most abundant polysaccharide in nature (behind only cellulose); an estimated 1 billion tons of chit ...
and specialized proteins, is released from the softer
epidermis The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the amount of water rele ...
beneath, and the epidermis begins to form a new cuticle. At the end of each instar, the larva moults, the old cuticle splits and the new cuticle expands, rapidly hardening and developing pigment. Development of butterfly wing patterns begins by the last larval instar. Caterpillars have short antennae and several
simple eyes A simple eye (sometimes called a pigment pit) refers to a form of eye or an optical arrangement composed of a single lens and without an elaborate retina such as occurs in most vertebrates. In this sense "simple eye" is distinct from a multi-le ...
. The
mouthparts Mouthparts may refer to: * The parts of a mouth ** Arthropod mouthparts *** Insect mouthparts {{disambig ...
are adapted for chewing with powerful mandibles and a pair of maxillae, each with a segmented palp. Adjoining these is the labium-hypopharynx which houses a tubular spinneret which is able to extrude silk. Caterpillars such as those in the genus '' Calpodes'' (family Hesperiidae) have a specialized tracheal system on the 8th segment that function as a primitive lung. Butterfly caterpillars have three pairs of true legs on the thoracic segments and up to six pairs of prolegs arising from the abdominal segments. These prolegs have rings of tiny hooks called crochets that are engaged hydrostatically and help the caterpillar grip the substrate. The epidermis bears tufts of setae, the position and number of which help in identifying the species. There is also decoration in the form of hairs, wart-like protuberances, horn-like protuberances and spines. Internally, most of the body cavity is taken up by the gut, but there may also be large silk glands, and special glands which secrete distasteful or toxic substances. The developing wings are present in later stage instars and the
gonad A gonad, sex gland, or reproductive gland is a mixed gland that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gonad, the testicle, produces sper ...
s start development in the egg stage.


Pupa

When the larva is fully grown, hormones such as prothoracicotropic hormone (PTTH) are produced. At this point the larva stops feeding, and begins "wandering" in the quest for a suitable pupation site, often the underside of a leaf or other concealed location. There it spins a button of silk which it uses to fasten its body to the surface and moults for a final time. While some caterpillars spin a cocoon to protect the pupa, most species do not. The naked pupa, often known as a chrysalis, usually hangs head down from the cremaster, a spiny pad at the posterior end, but in some species a silken girdle may be spun to keep the pupa in a head-up position. Most of the tissues and cells of the larva are broken down inside the pupa, as the constituent material is rebuilt into the imago. The structure of the transforming insect is visible from the exterior, with the wings folded flat on the ventral surface and the two halves of the proboscis, with the antennae and the legs between them. The pupal transformation into a butterfly through
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 ...
has held great appeal to mankind. To transform from the miniature wings visible on the outside of the pupa into large structures usable for flight, the pupal wings undergo rapid mitosis and absorb a great deal of nutrients. If one wing is surgically removed early on, the other three will grow to a larger size. In the pupa, the wing forms a structure that becomes compressed from top to bottom and pleated from proximal to distal ends as it grows, so that it can rapidly be unfolded to its full adult size. Several boundaries seen in the adult colour pattern are marked by changes in the expression of particular transcription factors in the early pupa.


Adult

The reproductive stage of the insect is the winged adult or imago. The surface of both butterflies and moths is covered by scales, each of which is an outgrowth from a single epidermal cell. The head is small and dominated by the two large compound eyes. These are capable of distinguishing flower shapes or motion but cannot view distant objects clearly. Colour perception is good, especially in some species in the blue/violet range. The antennae are composed of many segments and have clubbed tips (unlike moths that have tapering or feathery antennae). The sensory receptors are concentrated in the tips and can detect odours. Taste receptors are located on the palps and on the feet. The mouthparts are adapted to sucking and the mandibles are usually reduced in size or absent. The first maxillae are elongated into a tubular proboscis which is curled up at rest and expanded when needed to feed. The first and second maxillae bear palps which function as sensory organs. Some species have a reduced proboscis or maxillary palps and do not feed as adults. Many '' Heliconius'' butterflies also use their proboscis to feed on pollen; in these species only 20% of the amino acids used in reproduction come from larval feeding, which allow them to develop more quickly as caterpillars, and gives them a longer lifespan of several months as adults. The thorax of the butterfly is devoted to locomotion. Each of the three thoracic segments has two legs (among nymphalids, the first pair is reduced and the insects walk on four legs). The second and third segments of the thorax bear the wings. The leading edges of the forewings have thick veins to strengthen them, and the hindwings are smaller and more rounded and have fewer stiffening veins. The forewings and hindwings are not hooked together ( as they are in moths) but are coordinated by the friction of their overlapping parts. The front two segments have a pair of
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 which are used in respiration. The abdomen consists of ten segments and contains the gut and genital organs. The front eight segments have spiracles and the terminal segment is modified for reproduction. The male has a pair of clasping organs attached to a ring structure, and during copulation, a tubular structure is extruded and inserted into the female's vagina. A spermatophore is deposited in the female, following which the sperm make their way to a seminal receptacle where they are stored for later use. In both sexes, the genitalia are adorned with various spines, teeth, scales and bristles, which act to prevent the butterfly from mating with an insect of another species. After it emerges from its pupal stage, a butterfly cannot fly until the wings are unfolded. A newly emerged butterfly needs to spend some time inflating its wings with hemolymph and letting them dry, during which time it is extremely vulnerable to predators.


Pattern formation

The colorful patterns on many butterfly wings tell potential predators that they are toxic. Hence, the genetic basis of wing pattern formation can illuminate both the evolution of butterflies as well as their
developmental biology Developmental biology is the study of the process by which animals and plants grow and develop. Developmental biology also encompasses the biology of Regeneration (biology), regeneration, asexual reproduction, metamorphosis, and the growth and di ...
. The color of butterfly wings is derived from tiny structures called scales, each of which have their own pigments. In '' Heliconius'' butterflies, there are three types of scales: yellow/white, black, and red/orange/brown scales. Some mechanism of wing pattern formation are now being solved using genetic techniques. For instance, a gene called ''cortex'' determines the color of scales: deleting ''cortex'' turned black and red scales yellow. Mutations, e.g. transposon insertions of the non-coding DNA around the ''cortex'' gene can turn a black-winged butterfly into a butterfly with a yellow wing band.


Behaviour

Butterflies feed primarily on
nectar Nectar is a sugar-rich liquid produced by plants in glands called nectaries or nectarines, either within the flowers with which it attracts pollinating animals, or by extrafloral nectaries, which provide a nutrient source to animal mutualists ...
from flowers. Some also derive nourishment from
pollen Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophyt ...
, tree sap, rotting fruit, dung, decaying flesh, and dissolved minerals in wet sand or dirt. Butterflies are important as pollinators for some species of plants. In general, they do not carry as much pollen load as
bee Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyly, monophyletic lineage within the ...
s, but they are capable of moving pollen over greater distances. Flower constancy has been observed for at least one species of butterfly. Adult butterflies consume only liquids, ingested through the proboscis. They sip water from damp patches for hydration and feed on nectar from flowers, from which they obtain sugars for energy, and sodium and other minerals vital for reproduction. Several species of butterflies need more sodium than that provided by nectar and are attracted by sodium in salt; they sometimes land on people, attracted by the salt in human sweat. Some butterflies also visit dung and scavenge rotting fruit or carcasses to obtain minerals and nutrients. In many species, this mud-puddling behaviour is restricted to the males, and studies have suggested that the nutrients collected may be provided as a nuptial gift, along with the spermatophore, during mating. In hilltopping, males of some species seek hilltops and ridge tops, which they patrol in search for females. Since it usually occurs in species with low population density, it is assumed these landscape points are used as meeting places to find mates. Butterflies use their antennae to sense the air for wind and scents. The antennae come in various shapes and colours; the hesperiids have a pointed angle or hook to the antennae, while most other families show knobbed antennae. The antennae are richly covered with sensory organs known as sensillae. A butterfly's sense of taste is coordinated by chemoreceptors on the tarsi, or feet, which work only on contact, and are used to determine whether an egg-laying insect's offspring will be able to feed on a leaf before eggs are laid on it. Many butterflies use chemical signals, pheromones; some have specialized scent scales ( androconia) or other structures ( coremata or "hair pencils" in the Danaidae). Vision is well developed in butterflies and most species are sensitive to the ultraviolet spectrum. Many species show sexual dimorphism in the patterns of UV reflective patches. Colour vision may be widespread but has been demonstrated in only a few species. Some butterflies have organs of hearing and some species make
stridulatory 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 ...
and clicking sounds. Many species of butterfly maintain territories and actively chase other species or individuals that may stray into them. Some species will bask or perch on chosen perches. The flight styles of butterflies are often characteristic and some species have courtship flight displays. Butterflies can only fly when their temperature is above ; when it is cool, they can position themselves to expose the underside of the wings to the sunlight to heat themselves up. If their body temperature reaches , they can orientate themselves with the folded wings edgewise to the sun. Basking is an activity which is more common in the cooler hours of the morning. Some species have evolved dark wingbases to help in gathering more heat and this is especially evident in alpine forms. As in many other insects, the lift generated by butterflies is more than can be accounted for by steady-state, non-transitory aerodynamics. Studies using '' Vanessa atalanta'' in a wind tunnel show that they use a wide variety of aerodynamic mechanisms to generate force. These include wake capture, vortices at the wing edge, rotational mechanisms and the Weis-Fogh ' clap-and-fling' mechanism. Butterflies are able to change from one mode to another rapidly.


Ecology


Parasitoids, predators, and pathogens

Butterflies are threatened in their early stages by
parasitoid In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...
s and in all stages by predators, diseases and environmental factors. Braconid and other parasitic wasps lay their eggs in lepidopteran eggs or larvae and the wasps' parasitoid larvae devour their hosts, usually pupating inside or outside the desiccated husk. Most wasps are very specific about their host species and some have been used as biological controls of pest butterflies like the large white butterfly. When the
small cabbage white ''Pieris rapae'' is a small- to medium-sized butterfly species of the whites-and-yellows family Pieridae. It is known in Europe as the small white, in North America as the cabbage white or cabbage butterfly, on several continents as the small ca ...
was accidentally introduced to New Zealand, it had no natural enemies. In order to control it, some pupae that had been parasitised by a chalcid wasp were imported, and natural control was thus regained. Some flies lay their eggs on the outside of caterpillars and the newly hatched fly larvae bore their way through the skin and feed in a similar way to the parasitoid wasp larvae. Predators of butterflies include ants, spiders, wasps, and birds. Caterpillars are also affected by a range of bacterial, viral and fungal diseases, and only a small percentage of the butterfly eggs laid ever reach adulthood. The bacterium ''
Bacillus thuringiensis ''Bacillus thuringiensis'' (or Bt) is a gram-positive, soil-dwelling bacterium, the most commonly used biological pesticide worldwide. ''B. thuringiensis'' also occurs naturally in the gut of caterpillars of various types of moths and butterflie ...
'' has been used in sprays to reduce damage to crops by the caterpillars of the large white butterfly, and the entomopathogenic fungus ''Beauveria bassiana'' has proved effective for the same purpose.


Endangered species

Queen Alexandra's birdwing is the largest butterfly in the world. The species is List of endangered insects#Other Lepidoptera species, endangered, and is one of only three insects (the other two being butterflies as well) to be listed on CITES#Appendix I, Appendix I of CITES, making international trade illegal.CITES appendices I, II and III
, official website
Ocybadistes knightorum, Black grass-dart butterfly ''(Ocybadistes knightorum)'' is a butterfly of the family
Hesperiidae Skippers are a family of the Lepidoptera (moths and butterflies) named the Hesperiidae. Being diurnal, they are generally called butterflies. They were previously placed in a separate superfamily, Hesperioidea; however, the most recent taxonomy ...
. It is endemic to New South Wales. It has a very limited distribution in the Boambee, New South Wales, Boambee area.


Defences

Butterflies protect themselves from predators by a variety of means. Chemical defences are widespread and are mostly based on chemicals of plant origin. In many cases the plants themselves evolved these toxic substances as plant defense against herbivory, protection against herbivores. Butterflies have evolved mechanisms to sequester these plant toxins and use them instead in their own defence. These defence mechanisms are effective only if they are well advertised; this has led to the evolution of bright colours in unpalatable butterflies (
aposematism Aposematism is the advertising by an animal to potential predators that it is not worth attacking or eating. This unprofitability may consist of any defences which make the prey difficult to kill and eat, such as toxicity, venom, foul taste or ...
). This signal is commonly mimicry, mimicked by other butterflies, usually only females. A Batesian mimicry, Batesian mimic imitates another species to enjoy the protection of that species' aposematism. The Papilio polytes, common Mormon of India has female morphs which imitate the unpalatable red-bodied swallowtails, the Pachliopta aristolochiae, common rose and the Pachliopta hector, crimson rose. Müllerian mimicry occurs when aposematic species evolve to resemble each other, presumably to reduce predator sampling rates; '' Heliconius'' butterflies from the Americas are a good example. Camouflage is found in many butterflies. Some like the oakleaf butterfly and Doleschallia bisaltide, autumn leaf are remarkable imitations of leaves. As caterpillars, many defend themselves by freezing and appearing like sticks or branches. Others have deimatic behaviours, such as rearing up and waving their front ends which are marked with eyespots as if they were snakes. Some papilionid caterpillars such as the giant swallowtail (''Papilio cresphontes'') resemble bird droppings so as to be passed over by predators. Some caterpillars have hairs and bristly structures that provide protection while others are gregarious and form dense aggregations. Some species are myrmecophiles, forming Symbiosis, mutualistic associations with ants and gaining their protection. Behavioural defences include perching and angling the wings to reduce shadow and avoid being conspicuous. Some female Nymphalid butterflies guard their eggs from parasitoidal wasps. The Lycaenidae have a false head consisting of eyespots and small tails (false antennae) to deflect attack from the more vital head region. These may also cause ambush predators such as spiders to approach from the wrong end, enabling the butterflies to detect attacks promptly. Many butterflies have Eyespot (mimicry), eyespots on the wings; these too may deflect attacks, or may serve to attract mates. Auditory defences can also be used, which in the case of the grizzled skipper refers to vibrations generated by the butterfly upon expanding its wings in an attempt to communicate with ant predators. Many tropical butterflies have seasonal polyphenism, seasonal forms for dry and wet seasons. These are switched by the hormone ecdysone. The dry-season forms are usually more cryptic, perhaps offering better camouflage when vegetation is scarce. Dark colours in wet-season forms may help to absorb solar radiation. Butterflies without defences such as toxins or mimicry protect themselves through a flight that is more bumpy and unpredictable than in other species. It is assumed this behavior makes it more difficult for predators to catch them, and is caused by the turbulence created by the small whirlpools formed by the wings during flight.


Declining numbers

Declining butterfly populations have been noticed in many areas of the world, and this phenomenon is consistent with the decline in insect populations, rapidly decreasing insect populations around the world. At least in the Western United States, this collapse in the number of most species of butterflies has been determined to be driven by global climate change, specifically, by warmer autumns.


In culture


In art and literature

Butterflies have appeared in art from 3500 years ago in ancient Egypt. In the ancient Mesoamerican city of Teotihuacan, the brilliantly coloured image of the butterfly was carved into many temples, buildings, jewellery, and emblazoned on Censer, incense burners. The butterfly was sometimes depicted with the maw of a jaguar, and some species were considered to be the reincarnations of the souls of dead warriors. The close association of butterflies with fire and warfare persisted into the Aztec civilisation; evidence of similar jaguar-butterfly images has been found among the Zapotec peoples, Zapotec and Maya civilisations. Butterflies are widely used in objects of art and jewellery: mounted in frames, embedded in resin, displayed in bottles, laminated in paper, and used in some mixed media artworks and furnishings. The Norwegians, Norwegian naturalist Kjell B. Sandved, Kjell Sandved compiled a photographic ''Butterfly Alphabet'' containing all 26 letters and the numerals 0 to 9 from the wings of butterflies. Sir John Tenniel drew a famous illustration of Alice (Alice's Adventures in Wonderland), Alice meeting a Caterpillar (Alice's Adventures in Wonderland), caterpillar for Lewis Carroll's ''Alice's Adventures in Wonderland, Alice in Wonderland'', c. 1865. The caterpillar is seated on a toadstool and is smoking a hookah; the image can be read as showing either the forelegs of the larva, or as suggesting a face with protruding nose and chin. Eric Carle's children's book ''The Very Hungry Caterpillar'' portrays the larva as an extraordinarily hungry animal, while also teaching children how to count (to five) and the days of the week. A butterfly appeared in one of Rudyard Kipling's ''Just So Stories'', "The Butterfly that Stamped". One of the most popular, and most often recorded, songs by Sweden's eighteenth-century bard, Carl Michael Bellman, is "Fjäriln vingad syns på Haga" (The butterfly wingèd is seen in Haga), one of his ''Fredman's Songs''. ''Madam Butterfly'' is a 1904 opera by Giacomo Puccini about a romantic young Japanese bride who is deserted by her American officer husband soon after they are married. It was based on John Luther Long's short story written in 1898.


In mythology and folklore

According to Lafcadio Hearn, a butterfly was seen in Japan as the personification of a person's soul; whether they be living, dying, or already dead. One Japanese superstition says that if a butterfly enters your guest room and perches behind the bamboo screen, the person whom you most love is coming to see you. Large numbers of butterflies are viewed as bad omens. When Taira no Masakado was secretly preparing for his famous revolt, there appeared in Kyoto so vast a swarm of butterflies that the people were frightened—thinking the apparition to be a portent of coming evil. Diderot's ''Encyclopédie'' cites butterflies as a symbol for the soul. A Roman sculpture depicts a butterfly exiting the mouth of a dead man, representing the Roman belief that the soul leaves through the mouth. In line with this, the ancient Greek word for "butterfly" is ψυχή (''psȳchē''), which primarily means "soul" or "mind". According to Mircea Eliade, some of the Naga people, Nagas of Manipur claim ancestry from a butterfly.Rabuzzi, M. 1997. Butterfly etymology. Cultural Entomology November 1997 Fourth issu
online
In some cultures, butterflies symbolise Reincarnation, rebirth. The butterfly is a symbol of being transgender, because of the transformation from caterpillar to winged adult. In the English county of Devon, people once hurried to kill the first butterfly of the year, to avoid a year of bad luck. In the Philippines, a lingering black or dark butterfly or moth in the house is taken to mean an impending or recent death in the family. Several American states have chosen an List of U.S. state butterflies, official state butterfly.


Collecting, recording, and rearing

"Collecting" means preserving dead specimens, not keeping butterflies as pets. Collecting butterflies was once a popular hobby; it has now largely been replaced by photography, recording, and rearing butterflies for release into the wild. The zoological illustrator Frederick William Frohawk succeeded in rearing all the butterfly species found in Britain, at a rate of four per year, to enable him to draw every stage of each species. He published the results in the folio sized handbook ''The Natural History of British Butterflies'' in 1924. Butterflies and moths can be reared for recreation or for release.


In technology

Study of the structural coloration of the wing scales of swallowtail butterflies has led to the development of more efficient light-emitting diodes, and is inspiring nanotechnology research to produce paints that do not use toxic pigments and the development of new display technologies.


References


External links


Papilionoidea on the Tree of Life

Butterfly species and observations on iNaturalist
*
Rhopalocera
at insectoid.info


Regional lists


North America

AfricaGhana
* Asia
Indo-ChinaSulawesiTurkey
{{Authority control Butterflies, Articles containing video clips Extant Lutetian first appearances Insects in culture