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Hemiptera (; ) is an
order Order or ORDER or Orders may refer to: * Orderliness Orderliness is associated with other qualities such as cleanliness Cleanliness is both the abstract state of being clean and free from germs, dirt, trash, or waste, and the habit of achieving a ...
of
insect Insects (from Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" or "to be in ...

insect
s, commonly called true bugs, comprising over 80,000
species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individu ...

species
within groups such as the
cicada The cicadas () are a superfamily, the Cicadoidea, of insect Insects (from Latin ') are pancrustacean Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects ha ...

cicada
s,
aphid Aphids are small sap-sucking insects and members of the Taxonomic rank, superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white Erio ...

aphid
s,
planthopper A planthopper is any insect in the infraorder Fulgoromorpha, in the suborder Auchenorrhyncha, and exceeding 12,500 described species worldwide. The name comes from their remarkable resemblance to leaves and other plants of their environment and ...

planthopper
s,
leafhopper A leafhopper is the common name for any species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the la ...

leafhopper
s, bed bugs, and
shield bug The Pentatomoidea are a superfamily of insect Insects or Insecta (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area ...

shield bug
s. They range in size from to around , and share a common arrangement of sucking
mouthparts
mouthparts
. The name "true bugs" is often limited to the suborder
Heteroptera The Heteroptera are a group of about 40,000 species of insects in the order Hemiptera. They are sometimes called "true bugs", though that name more commonly refers to the Hemiptera as a whole. "Typical bugs" might be used as a more unequivocal alt ...

Heteroptera
. Many insects commonly known as "bugs", especially in
American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of variety (linguistics), varieties of the English language native to the United States. Currently, American English is the m ...
, belong to other orders; for example, the
lovebug The lovebug (''Plecia nearctica'') is a species of Bibionidae, march fly found in parts of Central America and the southeastern United States, especially along the Gulf Coast. It is also known as the honeymoon fly or double-headed bug. During and ...
is a
fly Flies are insect Insects or Insecta (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Lat ...

fly
and the
May bug The cockchafer, colloquially called Maybug or doodlebug, is the name given to any of the European beetles of the genus ''Melolontha'', in the family Scarabaeidae. Once abundant throughout Europe and a major pest in the periodical years of "mass f ...
and
ladybug Coccinellidae () is a widespread family In human society, family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of families is ...

ladybug
are
beetle Beetles are a group of insect Insects (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known a ...

beetle
s. Most hemipterans feed on plants, using their sucking and piercing mouthparts to extract plant sap. Some are
hematophagous File:Blood feeding butterflies 5362.JPG, Two butterflies of the genus '' Erebia'' sucking fresh blood from a sock Hematophagy (sometimes spelled haematophagy or hematophagia) is the practice by certain animals of feeding on blood (from the A ...
, while others are
predators 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 List of feeding behaviours, feeding behaviours that includes parasitism and micropredation (which ...
that feed on other insects or small invertebrates. They live in a wide variety of habitats, generally terrestrial, though some species are adapted to life in or on the surface of fresh water. Hemipterans are
hemimetabolous Hemimetabolism or hemimetaboly, also called incomplete Metamorphosis (biology), metamorphosis and paurometabolism,McGavin, George C. ''Essential Entomology: An Order-by-Order Introduction''. Oxford: Oxford University Press, 2001. pp. 20. is the mode ...
, with young
nymphs A nymph ( grc, νύμφη, nýmphē, el, script=Latn, nímfi, label=Modern Greek Modern Greek (, , or , ''Kiní Neoellinikí Glóssa''), generally referred to by speakers simply as Greek (, ), refers collectively to the dialects of the Gree ...
that somewhat resemble adults. Many aphids are capable of
parthenogenesis Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction Asexual reproduction is a typ ...
, producing young from unfertilised eggs; this helps them to reproduce extremely rapidly in favourable conditions. Humans have interacted with the Hemiptera for millennia. Some species, including many aphids, are significant
agricultural pests A pest is any animal or plant harmful to humans or human concerns. The term is particularly used for creatures that damage crops, livestock, and forestry or cause a nuisance to people, especially in their homes. Humans have modified the environm ...
, damaging crops by the direct action of sucking sap, but also harming them indirectly by being the
vectors Vector may refer to: Biology *Vector (epidemiology), an agent that carries and transmits an infectious pathogen into another living organism; a disease vector *Vector (molecular biology), a DNA molecule used as a vehicle to artificially carr ...
of serious viral diseases. Other species have been used for
biological control Biological control or biocontrol is a method of pest control, controlling pests such as insects, mites, weeds and phytopathology, plant diseases bioeffector, using other organisms. It relies on predation, parasitism, herbivory, or other natura ...
of insect pests. Hemipterans have been cultivated for the extraction of the dyestuff
cochineal The cochineal ( ; ; scientific name: ''Dactylopius coccus'') is a scale insect Scale insects are small insects of the Order (biology), order Hemiptera, suborder Sternorrhyncha. Of dramatically variable appearance and extreme sexual dimorphi ...
(also known as
carmine Carmine ()also called cochineal (for Cochineal, the insect from which it is extracted), cochineal extract, crimson Lake pigment, lake, or carmine lake is a pigment of a bright-red color obtained from the aluminium coordination complex, complex de ...

carmine
) and for
shellac Shellac () is a resin In polymer chemistry and materials science, resin is a solid or highly Viscosity, viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic co ...
. The bed bug is a persistent parasite of humans, and some
kissing bug The members of the Triatominae , a subfamily of the Reduviidae, are also known as conenose bugs, kissing bugs (so-called from their habit of feeding around the mouths of people), or vampire bugs. Other local names for them used in Latin America in ...
s can transmit
Chagas disease Chagas disease, also known as American trypanosomiasis, is a tropical disease, tropical parasitic disease caused by ''Trypanosoma cruzi''. It is spread mostly by insects known as ''Triatominae'', or "kissing bugs". The symptoms change over the ...
.
Cicada The cicadas () are a superfamily, the Cicadoidea, of insect Insects (from Latin ') are pancrustacean Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects ha ...

Cicada
s have been used as food, and have appeared in literature from the ''
Iliad The ''Iliad'' (; grc, Ἰλιάς, Iliás, ; sometimes referred to as the ''Song of Ilion'' or ''Song of Ilium'') is an in , traditionally attributed to . Usually considered to have been written down circa the 8th century BC, the ''Iliad'' i ...

Iliad
'' in
Ancient Greece Ancient Greece ( el, Ἑλλάς, Hellás) was a civilization belonging to a period of History of Greece, Greek history from the Greek Dark Ages of the 12th–9th centuries BC to the end of Classical Antiquity, antiquity ( AD 600). This era wa ...
.


Diversity

Hemiptera is the largest order of
hemimetabolous Hemimetabolism or hemimetaboly, also called incomplete Metamorphosis (biology), metamorphosis and paurometabolism,McGavin, George C. ''Essential Entomology: An Order-by-Order Introduction''. Oxford: Oxford University Press, 2001. pp. 20. is the mode ...
insects (not undergoing complete metamorphosis; though some examples such as male
scale insects Scale insects are small insects of the Order (biology), order Hemiptera, suborder Sternorrhyncha. Of dramatically variable appearance and extreme sexual dimorphism, they comprise the Taxonomic rank, superfamily Coccoidea. Adult females typically ...
do undergo a form of complete metamorphosis ), containing over 95,000 named species; insect orders with more species all have a
pupa A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insect Insects (from Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communicat ...

pupa
l stage (i.e. they do undergo complete metamorphosis or "
holometabolism Holometabolism, also called complete metamorphosis (biology), metamorphosis, is a form of insect development which includes four life stages: egg (biology), egg, larva, pupa, and imago (or adult). Holometabolism is a synapomorphy, synapomorphic tr ...
"),
Coleoptera Beetles are a group of insect Insects (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known a ...

Coleoptera
(>400,000 described species),
Lepidoptera Lepidoptera ( ; ) is an order Order or ORDER or Orders may refer to: * Orderliness Orderliness is associated with other qualities such as cleanliness Cleanliness is both the abstract state of being clean and free from germs, dirt, trash, or ...

Lepidoptera
(>180,000),
Hymenoptera Hymenoptera is a large order Order or ORDER or Orders may refer to: * Orderliness Orderliness is associated with other qualities such as cleanliness Cleanliness is both the abstract state of being clean and free from germs, dirt, trash, or wa ...

Hymenoptera
(150,000) and
Diptera Flies are insects of the Order (biology), order Diptera, the name being derived from the Ancient Greek, Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings ...

Diptera
(125,000). The majority of species are terrestrial, including a number of important agricultural pests, but some are found in freshwater habitats. These include the water boatmen, pond skaters, and giant water bugs.


Taxonomy and phylogeny

Hemiptera belong to the
insect Insects (from Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" or "to be in ...

insect
superorder In biological classification, the order ( la, ordo) is # a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also re ...
Paraneoptera Paraneoptera or Acercaria is a monophyletic Order (biology), superorder of insects which includes four extant orders, the Psocoptera, bark lice (which contains Louse, true lice), thrips, and hemipterans, the true bugs. It also includes a fifth ex ...
, which includes lice (
Psocodea Psocodea is a taxonomic group of insect Insects (from Latin ') are pancrustacean Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskel ...
), thrips (
Thysanoptera Thrips (Order (biology), order Thysanoptera) are minute (mostly 1 mm 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 cont ...

Thysanoptera
), and the true bugs of Hemiptera. Within Paraneoptera, Hemiptera is most closely related to the
sister clade In phylogenetics In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiolo ...
Thysanoptera. The
fossil record A fossil (from Classical Latin: , literally 'obtained by digging') is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, Seashell, shells, exoskeletons, stone imprints of a ...
of hemipterans goes back to the
Carboniferous The Carboniferous ( ) is a geologic period The geologic time scale (GTS) is a system of chronological dating that classifies Geology, geological strata (stratigraphy) in time. It is used by geologists, paleontology, paleontologists, and other ...
( Moscovian). The oldest fossils are of the Archescytinidae from the Lower Permian and are thought to be basal to the
Auchenorrhyncha The Auchenorrhyncha (former synonym: Cicadinea) suborder of the Hemiptera contains most of the familiar members of what was called the Homoptera – groups such as cicadas, leafhoppers, treehoppers, planthoppers, and spittlebugs. The aphids and sc ...

Auchenorrhyncha
. and
Cicadomorpha Cicadashterasdertaly is an infraorder of the order (biology), insect order Hemiptera which contains the cicadas, leafhoppers, treehoppers, and spittlebugs. There are approximately 35,000 described species worldwide. Distributed worldwide, all memb ...
appear in the
Upper Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous period million years ago (Mya), to the beginning of the Triassic period 251.902 Mya. It is the last period of the Pa ...
, as do
Sternorrhyncha The Sternorrhyncha suborder of the Hemiptera contains the aphids, whiteflies, and scale insects, groups which were traditionally included in the order Homoptera. "Sternorrhyncha" refers to the rearward position of the mouthparts relative to the ...
of the
Psylloidea PsylloideaOuvrard D: ''The World Psylloidea Database''
is a Aleyrodoidea.
Aphids Aphids are small sap SAP SE () is a German multinational software corporation based in Walldorf, Baden-Württemberg Baden-Württemberg (; ) is a States of Germany, state (''Land'') in southwest Germany, east of the Rhine, which for ...

Aphids
and Coccoids appear in the
Triassic The Triassic ( ) is a geologic period The geologic time scale (GTS) is a system of chronological dating that classifies Geology, geological strata (stratigraphy) in time. It is used by geologists, paleontology, paleontologists, and other earth ...

Triassic
. The
Coleorrhyncha Coleorrhyncha or Peloridiomorpha, also known as moss bugs or beetle bugs, are a suborder of Hemiptera and represent an ancient lineage of moss-feeding insects that evolved in the southern paleo-continent Gondwana. They show some similarities to the ...
extend back to the
Lower Jurassic The Early Jurassic epoch In chronology 222px, Joseph Scaliger's ''De emendatione temporum'' (1583) began the modern science of chronology Chronology (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, I ...
. The
Heteroptera The Heteroptera are a group of about 40,000 species of insects in the order Hemiptera. They are sometimes called "true bugs", though that name more commonly refers to the Hemiptera as a whole. "Typical bugs" might be used as a more unequivocal alt ...

Heteroptera
first appeared in the
Triassic The Triassic ( ) is a geologic period The geologic time scale (GTS) is a system of chronological dating that classifies Geology, geological strata (stratigraphy) in time. It is used by geologists, paleontology, paleontologists, and other earth ...

Triassic
. The present members of the order Hemiptera (sometimes referred to as Rhynchota) were historically placed into two orders, the so-called Homoptera and Heteroptera/Hemiptera, based on differences in wing structure and the position of the rostrum. The order is now divided into four suborders, after the "Homoptera" were established as
paraphyletic In taxonomy Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer to a specific classification scheme. Originally used only ...

paraphyletic
(now the
Auchenorrhyncha The Auchenorrhyncha (former synonym: Cicadinea) suborder of the Hemiptera contains most of the familiar members of what was called the Homoptera – groups such as cicadas, leafhoppers, treehoppers, planthoppers, and spittlebugs. The aphids and sc ...

Auchenorrhyncha
and the
Sternorrhyncha The Sternorrhyncha suborder of the Hemiptera contains the aphids, whiteflies, and scale insects, groups which were traditionally included in the order Homoptera. "Sternorrhyncha" refers to the rearward position of the mouthparts relative to the ...
). The below
cladogram A cladogram (from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is appr ...

cladogram
shows Hemiptera's placement within
Paraneoptera Paraneoptera or Acercaria is a monophyletic Order (biology), superorder of insects which includes four extant orders, the Psocoptera, bark lice (which contains Louse, true lice), thrips, and hemipterans, the true bugs. It also includes a fifth ex ...
, as well as how Hemiptera's four suborders are related. English names are given in parentheses where possible.


Biology


Mouthparts

The defining feature of hemipterans is their "beak" in which the modified
mandibles In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movable ...
and form a "stylet" which is sheathed within a modified labium. The stylet is capable of piercing tissues and sucking liquids, while the labium supports it. The stylet contains a channel for the outward movement of
saliva Saliva (commonly referred to as spit) is an extracellular fluid In cell biology Cell biology (also cellular biology or cytology) is a branch of biology Biology is the natural science that studies life and living organisms, including t ...
and another for the inward movement of liquid food. A salivary pump drives saliva into the prey; a cibarial pump extracts liquid from the prey. Both pumps are powered by substantial dilator muscles in the head. The beak is usually folded under the body when not in use. The diet is typically
plant sap SAP SE () is a German multinational Multinational may refer to: * Multinational corporation, a corporate organization operating in multiple countries * Multinational force, a military body from multiple countries * Multinational state, a sove ...

plant sap
, but some hemipterans such as
assassin bugs The Reduviidae are a large Cosmopolitan distribution, cosmopolitan family of the Order (biology), order Hemiptera (true bugs). Among the Hemiptera and together with the Nabidae almost all species are terrestrial ambush predators: most other predat ...

assassin bugs
are blood-suckers, and a few are
predators 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 List of feeding behaviours, feeding behaviours that includes parasitism and micropredation (which ...

predators
. Both herbivorous and predatory hemipterans inject
enzyme Enzymes () are proteins that act as biological catalysts (biocatalysts). Catalysts accelerate chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates in ...

enzyme
s to begin digestion extra-orally (before the food is taken into the body). These enzymes include
amylase An amylase () is an enzyme Enzymes () are protein Proteins are large s and s that comprise one or more long chains of . Proteins perform a vast array of functions within organisms, including , , , providing and , and from one lo ...
to hydrolyse
starch Starch or amylum is a polymeric A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance Substance may refer to: * Substance (Jainism), a term in Jain ontology to denote the base or owner of attributes * Chemical substance ...
,
polygalacturonase Polygalacturonase (), also known as pectin depolymerase, PG, ''pectolase'', ''pectin hydrolase'', and ''poly-alpha-1,4-galacturonide glycanohydrolase'', is an enzyme Enzymes () are proteins that act as biological catalysts (biocatalysts). Ca ...

polygalacturonase
to weaken the tough
cell wall A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane cell membrane vs. Prokaryotes The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to a ...
s of plants, and
proteinase A protease (also called a peptidase or proteinase) is an enzyme Enzymes () are proteins that act as biological catalysts (biocatalysts). Catalysts accelerate chemical reactions. The molecules upon which enzymes may act are called substrate (c ...
s to break down proteins. Although the Hemiptera vary widely in their overall form, their mouthparts form a distinctive "rostrum". Other insect orders with mouthparts modified into anything like the rostrum and stylets of the Hemiptera include some
Phthiraptera Louse (plural: lice) is the common name for members of the order (biology), order Phthiraptera, which contains nearly 5,000 species of wingless insect. Lice are obligate parasites, living externally on warm-blooded Host (biology), hosts which ...
, but for other reasons they generally are easy to recognize as non-hemipteran. Similarly, the mouthparts of
Siphonaptera Flea, the common name for the order Siphonaptera, includes 2,500 species of small flightless insect Insects or Insecta (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-E ...
, some
Diptera Flies are insect Insects (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Thro ...

Diptera
and
Thysanoptera Thrips (Order (biology), order Thysanoptera) are minute (mostly 1 mm 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 cont ...

Thysanoptera
superficially resemble the rostrum of the Hemiptera, but on closer inspection the differences are considerable. Aside from the mouthparts, various other insects can be confused with Hemiptera, but they all have biting mandibles and maxillae instead of the rostrum. Examples include
cockroach Cockroaches (or roaches) are insects of the order Blattodea, which also includes termites. About 30 cockroach species out of 4,600 are associated with human habitats. Some species are well-known as Pest (organism), pests. The cockroaches are ...

cockroach
es and , both of which have longer, many-segmented antennae, and some
beetle Beetles are a group of insect Insects (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known a ...

beetle
s, but these have fully hardened forewings which do not overlap.


Wing structure

The of Hemiptera are either entirely membranous, as in the
Sternorrhyncha The Sternorrhyncha suborder of the Hemiptera contains the aphids, whiteflies, and scale insects, groups which were traditionally included in the order Homoptera. "Sternorrhyncha" refers to the rearward position of the mouthparts relative to the ...
and
Auchenorrhyncha The Auchenorrhyncha (former synonym: Cicadinea) suborder of the Hemiptera contains most of the familiar members of what was called the Homoptera – groups such as cicadas, leafhoppers, treehoppers, planthoppers, and spittlebugs. The aphids and sc ...

Auchenorrhyncha
, or partially hardened, as in most
Heteroptera The Heteroptera are a group of about 40,000 species of insects in the order Hemiptera. They are sometimes called "true bugs", though that name more commonly refers to the Hemiptera as a whole. "Typical bugs" might be used as a more unequivocal alt ...

Heteroptera
. The name "Hemiptera" is from the
Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately 10.7 million as of ...
('; "half") and ('; "wing"), referring to the forewings of many heteropterans which are hardened near the base, but membranous at the ends. Wings modified in this manner are termed ''hemelytra'' (singular: ''hemelytron''), by analogy with the completely hardened
elytra An elytron (; ; ) is a modified, hardened forewing of beetles (Coleoptera), though a few of the true bugs (Hemiptera) such as the family Schizopteridae are extremely similar; in true bugs, the forewings are called hemelytra (sometimes alternati ...
of
beetle Beetles are a group of insect Insects (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known a ...

beetle
s, and occur only in the suborder
Heteroptera The Heteroptera are a group of about 40,000 species of insects in the order Hemiptera. They are sometimes called "true bugs", though that name more commonly refers to the Hemiptera as a whole. "Typical bugs" might be used as a more unequivocal alt ...

Heteroptera
. In all suborders, the hindwings – if present at all – are entirely membranous and usually shorter than the forewings. The forewings may be held "roofwise" over the body (typical of
Sternorrhyncha The Sternorrhyncha suborder of the Hemiptera contains the aphids, whiteflies, and scale insects, groups which were traditionally included in the order Homoptera. "Sternorrhyncha" refers to the rearward position of the mouthparts relative to the ...
and
Auchenorrhyncha The Auchenorrhyncha (former synonym: Cicadinea) suborder of the Hemiptera contains most of the familiar members of what was called the Homoptera – groups such as cicadas, leafhoppers, treehoppers, planthoppers, and spittlebugs. The aphids and sc ...

Auchenorrhyncha
), or held flat on the back, with the ends overlapping (typical of
Heteroptera The Heteroptera are a group of about 40,000 species of insects in the order Hemiptera. They are sometimes called "true bugs", though that name more commonly refers to the Hemiptera as a whole. "Typical bugs" might be used as a more unequivocal alt ...

Heteroptera
). The
antennae Antenna (pl. antennas or antennae) may refer to: Science and engineering * Antenna (radio), also known as an aerial, a transducer designed to transmit or receive electromagnetic (e.g., TV or radio) waves * Antennae Galaxies, the name of two coll ...
in Hemiptera typically consist of four or five segments, although they can still be quite long, and the tarsi of the
legs A leg is a weight-bearingIn orthopedics Orthopedic surgery or orthopedics, is the branch of surgery concerned with conditions involving the musculoskeletal system. Orthopedic surgeons use both surgical and nonsurgical means to treat muscul ...
have two or three segments.


Sound production

Many hemipterans can produce sound for communication. The "song" of male cicadas, the loudest of any insect, is produced by
tymbal The tymbal (or timbal) is the corrugated exoskeletal structure used to produce sounds in insects. In male cicada The cicadas () are a superfamily, the Cicadoidea, of insect Insects (from Latin ') are pancrustacean Hexapoda, hexapod inv ...
organs on the underside of the abdomen, and is used to attract mates. The tymbals are drumlike disks of cuticle, which are clicked in and out repeatedly, making a sound in the same way as popping the metal lid of a jam jar in and out. Stridulatory sounds are produced among the aquatic
Corixidae Corixidae is a family of aquatic insect Insects or Insecta (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around ...
and
Notonectidae Notonectidae is a cosmopolitan family of aquatic insects in the order Hemiptera, commonly called backswimmers because they swim upside down. They are all predator Predation is a biological interaction where one organism, the predator, kills ...
(backswimmers) using tibial combs rubbed across rostral ridges.


Life cycle

Hemipterans are
hemimetabolous Hemimetabolism or hemimetaboly, also called incomplete Metamorphosis (biology), metamorphosis and paurometabolism,McGavin, George C. ''Essential Entomology: An Order-by-Order Introduction''. Oxford: Oxford University Press, 2001. pp. 20. is the mode ...
, meaning that they do not undergo
metamorphosis Metamorphosis is a biological process Biological processes are those processes that are vital for an organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms are ...
, the complete change of form between a
larva A larva (plural larvae ) is a distinct juvenile form many animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism In biology, an organism () is any organic, life, living system that f ...
l phase and an . Instead, their young are called
nymphs A nymph ( grc, νύμφη, nýmphē, el, script=Latn, nímfi, label=Modern Greek Modern Greek (, , or , ''Kiní Neoellinikí Glóssa''), generally referred to by speakers simply as Greek (, ), refers collectively to the dialects of the Gree ...
, and resemble the adults to a greater or lesser degree. The nymphs moult several times as they grow, and each
instar An instar (, from the Latin ''īnstar'', "form", "likeness") is a developmental stage of arthropods An arthropod (, (gen. ποδός)) is an invertebrate Invertebrates are animals that neither possess nor develop a vertebral column (commonly ...
resembles the adult more than the previous one. Wing buds grow in later stage nymphs; the final transformation involves little more than the development of functional wings (if they are present at all) and functioning sexual organs, with no intervening
pupa A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insect Insects (from Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communicat ...

pupa
l stage as in
holometabolous Holometabolism, also called complete metamorphosis (biology), metamorphosis, is a form of insect development which includes four life stages: egg (biology), egg, larva, pupa, and imago (or adult). Holometabolism is a synapomorphy, synapomorphic tr ...
insects.


Parthenogenesis and viviparity

Many
aphid Aphids are small sap-sucking insects and members of the Taxonomic rank, superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white Erio ...

aphid
s are
parthenogenetic Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and development ...
during part of the life cycle, such that females can produce unfertilized eggs, which are
clones Clone or Clones or Cloning or The Clone may refer to: Places * Clones, County Fermanagh * Clones, County Monaghan, a town in Ireland Biology * Clone (B-cell), a lymphocyte clone, the massive presence of which may indicate a pathological conditio ...

clones
of their mother. All such young are females (
thelytoky Thelytoky (from the Greek ''thēlys'' "female" and ''tokos'' "birth") is a type of parthenogenesis in which females are produced from unfertilized eggs, as for example in aphids. Thelytokous parthenogenesis is rare among animals and reported in ...
), so 100% of the population at these times can produce more offspring. Many species of aphid are also
viviparous Among animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aero ...
: the young are born live rather than laid as eggs. These adaptations enable aphids to reproduce extremely rapidly when conditions are suitable.


Locomotion

Hemipterans make use of a variety of modes of
locomotion Locomotion means the act or ability of an entity or person to transport or move oneself from place to place. Locomotion or Loco-Motion may refer to: Motion * Motion (physics) *Specific types of motion ** Animal locomotion *** Terrestrial locomoti ...
including swimming, skating on a water surface and jumping, as well as walking and flying like other insects.


Swimming and skating

Several families of Heteroptera are ''water bugs'', adapted to an aquatic lifestyle, such as the water boatmen (Corixidae), water scorpions (Nepidae), and backswimmers (Notonectidae). They are mostly predatory, and have legs adapted as
paddle *When used for paddling Paddling with regard to watercraft is the act of manually propelling a boat using a paddle. The paddle, which consists of one or two blades joined to a shaft, is also used to steer the vessel. The paddle is not connec ...

paddle
s to help the animal move through the water. The pondskaters or water striders (Gerridae) are also associated with water, but use the
surface tension Surface tension is the tendency of liquid A liquid is a nearly incompressible In fluid mechanics Fluid mechanics is the branch of physics concerned with the mechanics Mechanics (Ancient Greek, Greek: ) is the area of physi ...

surface tension
of standing water to keep them above the surface; they include the sea skaters in the genus ''
Halobates ''Halobates'' or sea skaters are a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term m ...
'', the only truly marine group of insects.


Marangoni propulsion

Marangoni effect The Marangoni effect (also called the Gibbs–Marangoni effect) is the mass transfer along an Interface (chemistry), interface between two fluids due to a gradient of the surface tension. In the case of temperature dependence, this phenomenon may be ...
propulsion exploits the change in
surface tension Surface tension is the tendency of liquid A liquid is a nearly incompressible In fluid mechanics Fluid mechanics is the branch of physics concerned with the mechanics Mechanics (Ancient Greek, Greek: ) is the area of physi ...

surface tension
when a soap-like
surfactant Surfactants are compounds that lower the surface tension Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension is what allows objects with a higher density than wate ...

surfactant
is released on to a water surface, in the same way that a toy soap boat propels itself. Water bugs in the genus '''' (Veliidae) can travel at up to 17 cm/s, twice as fast as they can walk, by this means.


Flight

Flight is well developed in the Hemiptera although mostly used for short distance movement and dispersal. Wing development is sometimes related to environmental conditions. In some groups of Hemiptera, there are variations of winged, short-winged, and wingless forms within a single species. This kind of polymorphism tends to be helpful when habitats are temporary with more energy put into reproduction when food is available and into dispersal through flight when food becomes scarce. In aphids, both winged and wingless forms occur with winged forms produced in greater numbers when food resources are depleted. Aphids and whiteflies can sometimes be transported very long distances by atmospheric updrafts and high altitude winds. Wing-length polymorphism is notably rare in tree-living Hemiptera.


Jumping

Many Auchenorrhyncha including representatives of the cicadas, leafhoppers, treehoppers, planthoppers, and froghoppers are adapted for jumping (saltation). Treehoppers, for example, jump by rapidly depressing their hind legs. Before jumping, the hind legs are raised and the femora are pressed tightly into curved indentations in the coxae. Treehoppers can attain a take-off velocity of up to 2.7 metres per second and an acceleration of up to 250 g. The instantaneous power output is much greater than that of normal muscle, implying that energy is stored and released to catapult the insect into the air. Cicadas, which are much larger, extend their hind legs for a jump in under a millisecond, again implying elastic storage of energy for sudden release.


Sedentary

Instead of relying on any form of locomotion, most Sternorrhyncha females are sedentary or completely sessile, attached to their host plants by their thin feeding stylets which cannot be taken out of the plant quickly.


Ecological roles


Feeding modes


Herbivores

Most hemipterans are phytophagous, using their sucking and piercing mouthparts to feed on plant sap. These include cicadas, leafhoppers, treehoppers, planthoppers, froghoppers, aphids, whiteflies, scale insects, and some other groups. Some are Generalist and specialist species, monophages, being host specific and only found on one plant taxon, others are oligophages, feeding on a few plant groups, while others again are less discriminating Generalist and specialist species, polyphages and feed on many species of plant. The relationship between hemipterans and plants appears to be ancient, with piercing and sucking of plants evident in the Early Devonian period. Hemipterans can dramatically cut the mass of affected plants, especially in major outbreaks. They sometimes also change the mix of plants by predation on seeds or feeding on roots of certain species. Some sap-suckers move from one host to another at different times of year. Many aphids spend the winter as eggs on a woody host plant and the summer as Parthenogenesis, parthogenetically reproducing females on a herbaceous plant. Phloem sap, which has a higher concentration of sugars and nitrogen, is under positive pressure unlike the more dilute xylem sap. Most of the Sternorrhyncha and a number of Auchenorrhynchan groups feed on phloem. Phloem feeding is common in the Fulgoromorpha, most Cicadellidae and in the Heteroptera. The Typhlocybine Cicadellids specialize in feeding on non-vascular mesophyll tissue of leaves, which is more nutritious than the leaf epidermis. Most Heteroptera also feed on mesophyll tissue where they are more likely to encounter defensive secondary plant metabolites which often leads to the evolution of host specificity. Obligate xylem feeding is a special habit that is found in the Auchenorrhyncha among Cicadoidea, Cercopoidea and in Cicadelline Cicadellids. Some phloem feeders may take to xylem sap facultatively, especially when facing dehydration. Xylem feeders tend to be polyphagous; to overcome the negative pressure of xylem requires a special cibarial pump. Phloem feeding hemiptera typically have symbiotic micro-organisms in their gut that help to convert amino acids. Phloem feeders produce honeydew from their anus. A variety of organisms that feed on honeydew form symbiotic associations with phloem-feeders. Phloem sap is a sugary liquid low in amino acids, so insects have to process large quantities to meet their nutritional requirements. Xylem sap is even lower in amino acids and contains monosaccharides rather than sucrose, as well as organic acids and minerals. No digestion is required (except for the hydrolysis of sucrose) and 90% of the nutrients in the xylem sap can be utilised. Some phloem sap feeders selectively mix phloem and xylem sap to control the osmotic potential of the liquid consumed. A striking adaptation to a very dilute diet is found in many hemipterans: a filter chamber, a part of the gut looped back on itself as a countercurrent exchanger, which permits nutrients to be separated from excess water. The residue, mostly water with sugars and amino acids, is quickly excreted as sticky "honey dew", notably from aphids but also from other Auchenorrhycha and Sternorrhyncha. Some Sternorrhyncha including Psyllids and some aphids are gall formers. These sap-sucking hemipterans inject fluids containing plant hormones into the plant tissues inducing the production of tissue that covers to protects the insect and also act as sinks for nutrition that they feed on. The Pachypsylla, hackleberry gall psyllid for example, causes a woody gall on the leaf petioles of the Celtis occidentalis, hackleberry tree it infests, and the nymph of another psyllid produces a protective Lerp (biology), lerp out of hardened honeydew.


Predators

Most other hemipterans are predation, predatory, feeding on other insects, or even small vertebrates. This is true of many aquatic species which are predatory, either as nymphs or adults. The Cermatulus nasalis, predatory shield bug for example stabs caterpillars with its beak and sucks out the body fluids. The saliva of predatory heteropterans contains digestive enzymes such as
proteinase A protease (also called a peptidase or proteinase) is an enzyme Enzymes () are proteins that act as biological catalysts (biocatalysts). Catalysts accelerate chemical reactions. The molecules upon which enzymes may act are called substrate (c ...
and phospholipase, and in some species also
amylase An amylase () is an enzyme Enzymes () are protein Proteins are large s and s that comprise one or more long chains of . Proteins perform a vast array of functions within organisms, including , , , providing and , and from one lo ...
. The mouthparts of these insects are adapted for predation. There are toothed stylets on the mandibles able to cut into and abrade tissues of their prey. There are further stylets on the maxillae, adapted as tubular canals to inject saliva and to extract the pre-digested and liquified contents of the prey. Some species attack pest insects and are used in biological control. One of these is the spined soldier bug (''Podisus maculiventris'') that sucks body fluids from larvae of the Colorado beetle and the Mexican bean beetle.


Haematophagic "parasites"

A few hemipterans are Hematophagy, haematophagic (often described as "parasites"), feeding on the blood of larger animals. These include Bed bug (insect), bedbugs and the Triatominae, triatomine
kissing bug The members of the Triatominae , a subfamily of the Reduviidae, are also known as conenose bugs, kissing bugs (so-called from their habit of feeding around the mouths of people), or vampire bugs. Other local names for them used in Latin America in ...
s of the assassin bug family Reduviidae, which can transmit the dangerous ''
Chagas disease Chagas disease, also known as American trypanosomiasis, is a tropical disease, tropical parasitic disease caused by ''Trypanosoma cruzi''. It is spread mostly by insects known as ''Triatominae'', or "kissing bugs". The symptoms change over the ...
''. The first known hemipteran to feed in this way on vertebrates was the extinct assassin bug ''Triatoma dominicana'' found fossilized in amber and dating back about twenty million years. Faecal pellets fossilised beside it show that it transmitted a disease-causing ''Trypanosoma'' and the amber included hairs of the likely host, a bat.


As symbionts

Some species of ant protect and farm aphids (Sternorrhyncha) and other sap-sucking hemipterans, gathering and eating the Honeydew (secretion), honeydew that these hemipterans secrete. The relationship is mutualism (biology), mutualistic, as both ant and aphid benefit. Ants such as the yellow anthill ant, ''Lasius flavus'', breed aphids of at least four species, ''Geoica utricularia'', ''Tetraneura ulmi'', ''Forda marginata'' and ''Forda formicaria'', taking eggs with them when they found a new colony; in return, these aphids are obligately associated with the ant, breeding mainly or wholly asexually inside anthills. Ants may also protect the plant bugs from their natural enemies, removing the eggs of predatory beetles and preventing access by parasitic wasps. Some leafhoppers (Auchenorrhyncha) are similarly "milked" by ants. In the Corcovado rain forest of Costa Rica, wasps compete with ants to protect and milk leafhoppers; the leafhoppers preferentially give more honeydew, more often, to the wasps, which are larger and may offer better protection.


As prey: defences against predators and parasites

Hemiptera form prey to predators including vertebrates, such as birds, and other invertebrates such as ladybirds. In response, hemipterans have evolved antipredator adaptations. ''Ranatra'' may feign death (thanatosis). Others such as ''Carpocoris purpureipennis'' secrete toxin, toxic fluids to ward off arthropod predators; some Pentatomidae such as ''Dolycoris'' are able to direct these fluids at an attacker. Toxic cardenolide compounds are accumulated by the heteropteran ''Oncopeltus fasciatus'' when it consumes milkweeds, while the coreid stinkbug ''Amorbus rubiginosus'' acquires 2-hexenal from its food plant, ''Eucalyptus''. Some long-legged bugs mimic twigs, rocking to and fro to simulate the motion of a plant part in the wind. The nymph of the Reduvius personatus, Masked hunter bug Self-decoration camouflage, camouflages itself with sand grains, using its hind legs and tarsal fan to form a double layer of grains, coarser on the outside. The Amazon rain forest cicada ''Hemisciera maculipennis'' displays bright red deimatic flash coloration on its hindwings when threatened; the sudden contrast helps to startle predators, giving the cicada time to escape. The coloured patch on the hindwing is concealed at rest by an olive green patch of the same size on the forewing, enabling the insect to switch rapidly from crypsis, cryptic to deimatic behaviour. Some hemipterans such as Pyrrhocoris apterus, firebugs have bold aposematic warning coloration, often red and black, which appear to deter passerine birds. Many hemipterans including aphids, scale insects and especially the planthoppers secrete wax to protect themselves from threats such as fungi, parasitoidal insects and predators, as well as abiotic factors like desiccation. Hard waxy coverings are especially important in the sedentary Sternorrhyncha such as scale insects, which have no means of escaping from predators; other Sternorrhyncha evade detection and attack by creating and living inside plant galls. Nymphal Cicadoidea and Cercopoidea have glands attached to the Malpighian tubules in their proximal segment that produce mucopolysaccharides, which form the froth around spittlebugs, offering a measure of protection. Parental care is found in many species of Hemiptera especially in members of the Membracidae and numerous Heteroptera. In many species of shield bug, females stand guard over their egg clusters to protect them from egg parasitoids and predators. In the aquatic Belostomatidae, females lay their eggs on the back of the male which guards the eggs. Protection provided by ants is common in the Auchenorrhyncha.


Interaction with humans


As pests

Although many species of Hemiptera are significant pests of crops and garden plants, including many species of
aphid Aphids are small sap-sucking insects and members of the Taxonomic rank, superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white Erio ...

aphid
and scale insects, other species are harmless. The damage done is often not so much the deprivation of the plant of its sap, but the fact that they transmit serious viral diseases between plants. They often produce copious amounts of honeydew (secretion), honeydew which encourages the growth of Sooty mold, sooty mould. Significant pests include the Icerya purchasi, cottony cushion scale, a pest of citrus fruit trees, the Myzus persicae, green peach aphid and other aphids which attack crops worldwide and transmit diseases, and Jumping plant louse#Status as pests, jumping plant lice which are often host plant-specific and transmit diseases.


For pest control

Members of the families Reduviidae, Phymatidae and Nabidae are obligate predators. Some predatory species are used in biological pest control; these include various Nabidae, nabids, and even some members of families that are primarily phytophagous, such as the genus ''Geocoris'' in the family Lygaeidae. Other hemipterans are omnivores, alternating between a plant-based and an animal-based diet. For example, ''Dicyphus hesperus'' is used to control whitefly on tomatoes but also sucks sap, and if deprived of plant tissues will die even if in the presence of whiteflies.


Insect products

Other hemipterans have positive uses for humans, such as in the production of the dyestuff
carmine Carmine ()also called cochineal (for Cochineal, the insect from which it is extracted), cochineal extract, crimson Lake pigment, lake, or carmine lake is a pigment of a bright-red color obtained from the aluminium coordination complex, complex de ...

carmine
(
cochineal The cochineal ( ; ; scientific name: ''Dactylopius coccus'') is a scale insect Scale insects are small insects of the Order (biology), order Hemiptera, suborder Sternorrhyncha. Of dramatically variable appearance and extreme sexual dimorphi ...
). The FDA has created guidelines for how to declare when it has been added to a product. The scale insect ''Dactylopius coccus'' produces the brilliant red-coloured carminic acid to deter predators. Up to 100,000 scale insects need to be collected and processed to make a kilogram (2.2 lbs) of cochineal dye. A similar number of Kerria lacca, lac bugs are needed to make a kilogram of
shellac Shellac () is a resin In polymer chemistry and materials science, resin is a solid or highly Viscosity, viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic co ...
, a brush-on colourant and wood finish. Additional uses of this traditional product include the waxing of citrus fruits to extend their shelf-life, and the coating of pills to moisture-proof them, provide slow-release or mask the taste of bitter ingredients.


As human parasites and disease vectors

Chagas disease Chagas disease, also known as American trypanosomiasis, is a tropical disease, tropical parasitic disease caused by ''Trypanosoma cruzi''. It is spread mostly by insects known as ''Triatominae'', or "kissing bugs". The symptoms change over the ...
is a modern-day tropical disease caused by ''Trypanosoma cruzi'' and transmitted by Triatominae, kissing bugs, so-called because they suck human blood from around the lips while a person sleeps. The bed bug, ''Cimex lectularius'', is an external parasite of humans. It lives in bedding and is mainly active at night, feeding on human blood, generally without being noticed. Bed bugs Mating, mate by traumatic insemination; the male pierces the female's abdomen and injects his sperm into a secondary genital structure, the spermalege. The sperm travel in the female's blood (haemolymph) to female sperm storage, sperm storage structures (seminal conceptacles); they are released from there to fertilise her eggs inside her ovaries.Carayon, J. 1959 Insémination par "spermalège" et cordon conducteur de spermatozoids chez Stricticimex brevispinosus Usinger (Heteroptera, Cimicidae). Rev. Zool. Bot. Afr. 60, 81–104.


As food

Some larger hemipterans such as
cicada The cicadas () are a superfamily, the Cicadoidea, of insect Insects (from Latin ') are pancrustacean Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects ha ...

cicada
s are used as food in Asian countries such as China, and they are much esteemed in Malawi and other African countries. Insects have a high protein content and good food conversion ratios, but most hemipterans are too small to be a useful component of the human diet. At least nine species of Hemiptera are eaten worldwide.


In art and literature

Cicadas have featured in literature since the time of Homer's ''
Iliad The ''Iliad'' (; grc, Ἰλιάς, Iliás, ; sometimes referred to as the ''Song of Ilion'' or ''Song of Ilium'') is an in , traditionally attributed to . Usually considered to have been written down circa the 8th century BC, the ''Iliad'' i ...

Iliad
'', and as motifs in decorative art from the Chinese Shang dynasty (1766–1122 B.C.). They are described by Aristotle in his ''History of Animals'' and by Pliny the Elder in his ''Natural History (Pliny), Natural History''; their mechanism of sound production is mentioned by Hesiod in his poem ''Works and Days'' "when the Skolymus flowers, and the tuneful ''Tettix'' sitting on his tree in the weary summer season pours forth from under his wings his shrill song".


In mythology and folklore

Among the bugs, cicadas in particular have been used as money, in folk medicine, to forecast the weather, to provide song (in China), and in folklore and myths around the world.


Threats

Large-scale cultivation of the oil palm ''Elaeis guineensis'' in the Amazon basin damages freshwater habitats and reduces the diversity of aquatic and semi-aquatic Heteroptera. Climate change may be affecting the global migration of hemipterans including the potato leafhopper, ''Empoasca fabae''. Warming is correlated with the severity of potato leafhopper infestation, so increased warming may worsen infestations in future.


Notes


References


External links


Cladogram of Hemiptera at Tree of Life Project
{{Authority control Hemiptera, Insect orders Extant Pennsylvanian first appearances Taxa named by Carl Linnaeus