hemiptera

Hemiptera is the largest order of hemimetabolous insects (not undergoing complete metamorphosis; though some examples such as male scale insects do undergo a form of complete metamorphosis {{cite journal|last1=Gullan |first1=Penny |last2=Kosztarab |first2=Michael |title=Adaptations in scale insects |journal=Annual Review of Entomology |date=1997 |volume=42 |pages=23–50 |doi=10.1146/annurev.ento.42.1.23 |pmid=15012306 }}), containing over 95,000 named species. Other insect orders with more species are all holometabolous, meaning they have a pupal stage and undergo complete metamorphosis. 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, backswimmers, pond skaters, and giant water bugs.

Hemiptera belong to the insect superorder Paraneoptera, which includes lice (Psocodea), thrips (Thysanoptera), and the true bugs of Hemiptera. Within Paraneoptera, Hemiptera is most closely related to the sister clade Thysanoptera.{{cite journal |last=Johnson |first=Kevin P. |last2=Dietrich |first2=Christopher H. |last3=Friedrich |first3=Frank |last4=Beutel |first4=Rolf G. |last5=Wipfler |first5=Benjamin |last6=Peters |first6=Ralph S. |last7=Allen |first7=Julie M. |last8=Petersen |first8=Malte |last9=Donath |first9=Alexander |last10=Walden |first10=Kimberly K. O. |last11=Kozlov |first11=Alexey M. |last12=Podsiadlowski |first12=Lars |last13=Mayer |first13=Christoph |last14=Meusemann |first14=Karen |last15=Vasilikopoulos |first15=Alexandros |last16=Waterhouse |first16=Robert M. |last17=Cameron |first17=Stephen L. |last18=Weirauch |first18=Christiane |last19=Swanson |first19=Daniel R. |last20=Percy |first20=Diana M. |last21=Hardy |first21=Nate B. |last22=Terry |first22=Irene |last23=Liu |first23=Shanlin |last24=Zhou |first24=Xin |last25=Misof |first25=Bernhard |last26=Robertson |first26=Hugh M. |last27=Yoshizawa |first27=Kazunori |display-authors=5 |title=Phylogenomics and the evolution of hemipteroid insects |journal=Proceedings of the National Academy of Sciences |publisher=Proceedings of the National Academy of Sciences |volume=115 |issue=50 |date=2018-11-26 |doi=10.1073/pnas.1815820115 |doi-access=free |pages=12775–12780 |hdl=2115/75518 |hdl-access=free }}

File:Fulgoroidea Crato Formation Brazil.jpg (Fulgoromorpha) from the Early Cretaceous Crato Formation of Brazil, c. 116 mya]]

The fossil record of hemipterans goes back to the Carboniferous (Moscovian).{{cite journal |last=Nel |first=André |last2=Roques |first2=Patrick |last3=Nel |first3=Patricia |last4=Prokin |first4=Alexander A. |last5=Bourgoin |first5=Thierry |last6=Prokop |first6=Jakub |last7=Szwedo |first7=Jacek |last8=Azar |first8=Dany |last9=Desutter-Grandcolas |first9=Laure |last10=Wappler |first10=Torsten |last11=Garrouste |first11=Romain |last12=Coty |first12=David |last13=Huang |first13=Diying |last14=Engel |first14=Michael S. |last15=Kirejtshuk |first15=Alexander G. |display-authors=5 |title=The earliest known holometabolous insects |journal=Nature |publisher=Springer Science and Business Media |volume=503 |issue=7475 |date=2013-10-16 |doi=10.1038/nature12629 |pages=257–261}} The oldest fossils are of the Archescytinidae from the Lower Permian and are thought to be basal to the Auchenorrhyncha. Fulgoromorpha and Cicadomorpha appear in the Upper Permian, as do Sternorrhyncha of the Psylloidea and Aleyrodoidea. Aphids and Coccoids appear in the Triassic. The Coleorrhyncha extend back to the Lower Jurassic.{{cite book|page=213|author=Gillott, Cedric|title=Entomology|edition=3|year=2005|publisher= Springer}} The Heteroptera first appeared in the Triassic.{{cite journal |author=Shcherbakov, D. E. |year=2000 |title=Permian faunas of Homoptera (Hemiptera) in relation to phytogeography and the Permo-Triassic crisis |journal=Paleontological Journal |volume=34 |issue=3 |pages=S251–S267 |url=http://palaeoentomolog.ru/Publ/PALS251.pdf}}

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. "Homoptera" was established as paraphyletic group and an obsolete name.Dudley R. (2002). [https://books.google.com/books?id=hTIMhD9BF1kC&pg=PA184&lpg=PA184 The biomechanics of insect flight: Form, function, evolution]. Princeton, NJ: Princeton University Press. p 184. {{ISBN|0-691-09491-8}}.{{cite journal |last1=Von Dohlen |first1=C.D. |last2=Moran |first2=N.A. |year=1995 |title=Molecular phylogeny of the Homoptera: a paraphyletic taxon |url=http://ag.udel.edu/delpha/1158.pdf |journal=Journal of Molecular Evolution |volume=41 |issue=2 |pages=211–223 |doi=10.1007/BF00170675 |pmid=7666451 |bibcode=1995JMolE..41..211V |s2cid=20275322 |access-date=2011-05-24 |archive-url=https://web.archive.org/web/20110928185057/http://ag.udel.edu/delpha/1158.pdf |archive-date=2011-09-28 |url-status=dead }}{{Cite journal|url=http://169.237.77.3/gullanandcranstonlab/Gullanpdfs/Homoptera.pdf |archive-url=https://web.archive.org/web/20150122132644/http://169.237.77.3/gullanandcranstonlab/Gullanpdfs/Homoptera.pdf |url-status=dead |archive-date=2015-01-22 |last=Gullan |first=P.J. |journal=Entomologica |volume=33 |year=1999 |pages=101–104 |title=Why the taxon Homoptera does not exist }}

The order is now divided into four suborders, Heteroptera, Sternorrhyncha, Auchenorrhyncha, and Coleorrhyncha.{{cite journal |last1=Song |first1=Nan |last2=Liang |first2=Ai-Ping |last3=Bu |first3=Cui-Ping |title=A Molecular Phylogeny of Hemiptera Inferred from Mitochondrial Genome Sequences |journal=PLOS ONE |date=2012 |volume=7 |issue=11 |pages=e48778 |doi=10.1371/journal.pone.0048778 |pmid=23144967 |bibcode=2012PLoSO...748778S |pmc=3493603 |doi-access=free }}{{cite journal |last=Forero |first=Dimitri |title=The Systematics of Hemiptera |journal=Revista Colombiana de Entomología |volume=34 |issue=1 |date=2008 |pages=1–21 |doi=10.25100/socolen.v34i1.9244 |s2cid=85830606 |url=http://www.scielo.org.co/pdf/rcen/v34n1/v34n1a01.pdf |url-status=dead |archive-url=https://web.archive.org/web/20150113135356/http://www.scielo.org.co/pdf/rcen/v34n1/v34n1a01.pdf |archive-date=January 13, 2015 }}{{cite journal |last1=Cryan |first1=Jason C. |last2=Urban |first2=Julie M. |title=Higher-level phylogeny of the insect order Hemiptera: is Auchenorrhyncha really paraphyletic? |journal=Systematic Entomology |date=January 2012 |volume=37 |issue=1 |pages=7–21 |doi=10.1111/j.1365-3113.2011.00611.x|bibcode=2012SysEn..37....7C |s2cid=86564882 }}{{Cite book|author1=Schuh, Randall T. |author2=Slater, James Alexander |year=1995 |title=True bugs of the world (Hemiptera: Heteroptera): classification and natural history|location=Ithaca, New York|publisher=Cornell University Press |pages=[https://books.google.com/books?id=wmSc-2KDmZ4C&pg=PA4 4–5]|isbn=978-0-8014-2066-5}}{{Cite book |last=Cobben |first=René Hubert |year=1978 |title=Evolutionary trends in Heteroptera, part 2: mouthpart-structures and feeding strategies |series=Verslagen van landbouwkundige onderzoekingen, number 707 |location=Wageningen, Netherlands |publisher=H. Veenman for Centrum voor Landbouwpublikaties en Landbouwdocumentatie |page=7 |oclc=852739989}} The earlier work was based on nuclear DNA, but later phylogenetic analysis using mitochondrial DNA suggests that Homoptera may be monophyletic after all, a sister group of Heteroptera.{{cite journal |last1=Song |first1=N. |last2=Liang |first2=A.-P. |last3=Bu |first3=C.-P. |year=2012 |title=A Molecular Phylogeny of Hemiptera Inferred from Mitochondrial Genome Sequences |journal=PLOS ONE |volume=7 |issue=11 |pages=e48778 |doi=10.1371/journal.pone.0048778 |pmc=3493603 |pmid=23144967 |bibcode=2012PLoSO...748778S |doi-access=free }} The cause of the disparity in the analyses is suggested to be the long branch attraction effect in phylogenetic analysis, due to rapidly evolving DNA regions.

The cladogram shows Hemiptera's placement within Paraneoptera, as well as how Hemiptera's four suborders are related. English names are given in parentheses where possible.

{{clade

|1=Other insects 70px

|label2=Paraneoptera

|2={{clade

|label1=Psocodea

|1=(barklice, booklice, lice) 70px

|label2=Condylognatha

|2={{clade

|1=Thysanoptera (thrips) 70px

|label2=Hemiptera |sublabel2=(true bugs)

|2={{clade

|label1=Sternorrhyncha

|1= (aphids, scale insects, etc) 70px

|2={{clade

|label1= Heteroptera

|1= (shield bugs, assassin bugs, etc) 60px

|2={{clade

|label1= Coleorrhyncha

|1= (moss bugs) 55px

|label2= Auchenorrhyncha

|2={{clade

|1= Fulgoromorpha (planthoppers) 70px

|2= Cicadomorpha (cicadas, leafhoppers, spittlebugs, etc) 70px

}} }} }} }} }} }} }}

File:HemipteraMouthparts.jpg and maxillae modified to form a piercing "stylet" sheathed within a modified labium.]]

File:Milkweed bug drilling.webm nymph feeding on milkweed before extracting its stylet, sheathing it again in its rostrum.]]

The defining feature of hemipterans is their "beak" in which the modified mandibles and maxillae 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 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, but some hemipterans such as assassin bugs are predators.{{cite book |title=Invertebrate Zoology, 7th edition |last1=Ruppert |first1=Edward E. |last2=Fox |first2=Richard, S. |last3=Barnes |first3=Robert D. |year=2004 |publisher=Cengage Learning |isbn=978-81-315-0104-7 |pages=728, 748 }}

Both herbivorous and predatory hemipterans inject enzymes to begin digestion extra-orally (before the food is taken into the body). These enzymes include amylase to hydrolyse starch, polygalacturonase to weaken the tough cell walls of plants, and proteinases to break down proteins.{{cite book |last=Wheeler |first=Alfred George |title=Biology of the Plant Bugs (Hemiptera: Miridae): Pests, Predators, Opportunists |url=https://books.google.com/books?id=0szFXwGVlo4C&pg=PA105 |year=2001 |publisher=Cornell University Press|isbn=978-0-8014-3827-1 |pages=105–135}}

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, but for other reasons they generally are easy to recognize as non-hemipteran. Similarly, the mouthparts of Siphonaptera, some Diptera and 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 cockroaches and psocids, both of which have longer, many-segmented antennae, and some beetles, but these have fully hardened forewings which do not overlap.{{cite book |last=Chinery |first=Michael |title=A Field Guide to the Insects of Britain and Northern Europe |edition=3rd |publisher=Collins |year=1993 |isbn=978-0-00-219918-6 |chapter=Order Hemiptera – The True Bugs |page=115}}

The forewings of Hemiptera are either entirely membranous, as in the Sternorrhyncha and Auchenorrhyncha, or partially hardened, as in most Heteroptera. The name "Hemiptera" is from the Greek {{lang|el|ἡμι-}} ({{lang|el|hemi}}; "half") and {{lang|el|πτερόν}} ({{lang|el|pteron}}; "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 of beetles, and occur only in the suborder Heteroptera. In all suborders, the hindwings – if present at all – are entirely membranous and usually shorter than the forewings.{{cite book|author1=Coulson, Robert N.|author2=Witter, John A.|title=Forest Entomology: Ecology and Management |url=https://books.google.com/books?id=-QsVpIEsuLcC&pg=PA71 |year=1984 |publisher=John Wiley & Sons |isbn=978-0-471-02573-3 |pages=71–72}} The forewings may be held "roofwise" over the body (typical of Sternorrhyncha and Auchenorrhyncha),{{cite book|author=Alford, David V.|title=Pests of Ornamental Trees, Shrubs and Flowers: A Color Handbook |url=https://books.google.com/books?id=c9PwiScwmPIC&pg=PA12 |year=2012 |publisher=Academic Press |isbn=978-0-12-398515-6 |page=12}} or held flat on the back, with the ends overlapping (typical of Heteroptera). The antennae in Hemiptera typically consist of four or five segments, although they can still be quite long, and the tarsi of the legs have two or three segments.{{cite web |url=http://www.discoverlife.org/mp/20q?search=Hemiptera |title=Hemiptera |publisher=Discover Life |access-date=13 July 2015}}

{{further|Tymbal|Stridulation}}

Many hemipterans can produce sound for communication.{{cite journal|last1=Virant-Doberlet|first1=Meta|last2=Cokl|first2=Andrej|title=Vibrational Communication in Insects|journal=Neotropical Entomology|date=April 2004|volume=33|issue=2|doi=10.1590/S1519-566X2004000200001|pages=121–134|doi-access=free}} The "song" of male cicadas, the loudest of any insect, is produced by tymbal 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.{{cite journal |last1=Simmons |first1=Peter |last2=Young |first2=David |title=The Tymbal Mechanism and Song Patterns of the Bladder Cicada, Cystosoma saundersii |journal=Journal of Experimental Biology |date=1978 |volume=76 |pages=27–45 |doi=10.1242/jeb.76.1.27 |url=http://download.naturkundemuseum-berlin.de/andreas.wessel/Cicada_morphology/simmons_young_1978_cystosoma_saundersii_tymbal_mechanism.pdf |access-date=2015-08-22 |archive-url=https://web.archive.org/web/20151224214649/http://download.naturkundemuseum-berlin.de/andreas.wessel/Cicada_morphology/simmons_young_1978_cystosoma_saundersii_tymbal_mechanism.pdf |archive-date=2015-12-24 |url-status=dead }}

Stridulatory sounds are produced among the aquatic Corixidae and Notonectidae (backswimmers) using tibial combs rubbed across rostral ridges.{{cite journal |last1=Wilcox |first1=R. Stimson |title=Sound-producing Mechanisms of Bueno macrotibialis Hungerford (Hemiptera: Notonectidae) |journal=International Journal of Insect Morphology & Embryology |year=1975 |volume=4 |issue=21 |pages=169–182 |url=http://deepblue.lib.umich.edu/bitstream/handle/2027.42/22083/0000507.pdf?sequence=1 |doi=10.1016/0020-7322(75)90015-x|hdl=2027.42/22083 |hdl-access=free }}{{cite book|author1=Gooderham, John|author2=Tsyrlin, Edward|title=The Waterbug Book: A Guide to the Freshwater Macroinvertebrates of Temperate Australia |url=https://books.google.com/books?id=0_Paklse3XcC&pg=PA146|year=2002 |publisher=Csiro Publishing |isbn=978-0-643-06668-7 |page=146}}

File:Ant-mimic predatory bug, Myrmecoris gracilis, on Yarrow.JPG predatory bug Myrmecoris gracilis]]

Hemipterans are hemimetabolous, meaning that they do not undergo metamorphosis, the complete change of form between a larval phase and an adult phase. Instead, their young are called nymphs, and resemble the adults to a greater or lesser degree. The nymphs moult several times as they grow, and each instar 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 pupal stage as in holometabolous insects.{{cite web |url=https://australian.museum/learn/animals/insects/ |title=Metamorphosis: a remarkable change |author=Britton, David |date=9 July 2009 |publisher=Australian Museum |access-date=13 July 2015}}

File:Aphid-giving-birth.jpg

{{further|parthenogenesis|thelytoky|viviparity}}

Many aphids are parthenogenetic during part of the life cycle, such that females can produce unfertilized eggs, which are clones of their mother. All such young are females (thelytoky), so 100% of the population at these times can produce more offspring. Many species of aphid are also viviparous: the young are born live rather than laid as eggs. These adaptations enable aphids to reproduce extremely rapidly when conditions are suitable.{{cite web |url=http://www.biology-resources.com/aphid-01.html |title=Aphids, an Introduction |author=Mackean, D.G. |work=Biology Teaching Resources |access-date=13 July 2015}}

File:Wasserläufer bei der Paarung crop.jpgs are adapted to use surface tension to keep above a freshwater surface.]]

{{further|Animal locomotion}}

Hemipterans make use of a variety of modes of locomotion including swimming, skating on a water surface and jumping, as well as walking and flying like other insects.

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 paddles to help the animal move through the water.{{cite web |url=http://www.nhm.ac.uk/resources-rx/files/26feat_its_a_bugs_life-3013.pdf |title=Hemiptera...It's a Bug's Life |publisher=Natural History Museum |author1=Jon Martin |author2=Mick Webb |access-date=July 26, 2010}} The pondskaters or water striders (Gerridae) are also associated with water, but use the surface tension of standing water to keep them above the surface; they include the sea skaters in the genus Halobates, the only truly marine group of insects.

File:MicroveliaIndia.jpg water bugs using Marangoni propulsion]]

Marangoni effect propulsion exploits the change in surface tension when a soap-like surfactant is released on to a water surface, in the same way that a toy soap boat propels itself. Water bugs in the genus Microvelia (Veliidae) can travel at up to 17 cm/s, twice as fast as they can walk, by this means.{{cite journal |author1=Bush, John W. M. |author2=Hu, David L. |doi=10.1146/annurev.fluid.38.050304.092157 |title=Walking on Water: Biolocomotion at the Interface |journal=Annual Review of Fluid Mechanics |volume=38 |issue=1 |pages=339–369 |year=2006 | bibcode=2006AnRFM..38..339B}}

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.{{cite journal |author1= Loxdale, H. D. |author2= Hardie, J. |author3=Halbert, S. |author4=Foottit, R. |author5=Kidd, N. A. C. |author6= Carter, C. I. |year=1993 | title=The relative importance of short- and long-range movement of flying aphids |journal=Biological Reviews |volume=68 |issue=2 |pages=291–311 |doi=10.1111/j.1469-185X.1993.tb00998.x |s2cid=86569822 |url=https://repository.rothamsted.ac.uk/download/77c13e9643abcf2d2cf90fc3220ffa990d82288834c9054e15a503ee7a0a16de/16412309/The_relative_importance_of_short-_and_long-range_m.pdf}} Wing-length polymorphism is notably rare in tree-living Hemiptera.{{cite journal |last1=Waloff |first1=Nadia |author-link=Nadia Waloff |doi=10.1111/j.1365-2311.1983.tb00502.x |title=Absence of wing polymorphism in the arboreal, phytophagous species of some taxa of temperate Hemiptera: An hypothesis |journal=Ecological Entomology |volume=8 |issue=2 |pages=229–232 |year=1983 |bibcode=1983EcoEn...8..229W |s2cid=83833159}}

{{further|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.{{cite journal |last1=Burrows |first1=M. |title=Jumping mechanisms of treehopper insects (Hemiptera, Auchenorrhyncha, Membracidae) |journal=Journal of Experimental Biology |date=March 2013 |volume= 216|issue=5 |pages=788–799 |doi=10.1242/jeb.078741 |pmid=23155084|doi-access=free }} 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.{{cite journal |last1=Gorb |first1=S. N. |title=The jumping mechanism of cicada Cercopis vulnerata (Auchenorrhyncha, Cercopidae): skeleton-muscle organisation, frictional surfaces, and inverse-kinematic model of leg movements |journal=Arthropod Structure & Development |date=July 2004 |volume=33 |issue=3 |pages=201–220 |doi=10.1016/j.asd.2004.05.008 |pmid=18089035|bibcode=2004ArtSD..33..201G }}

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.{{cite book |last1=Grimaldi |first1=David |last2=Engel |first2=Michael S. |title=Evolution of the Insects |url=https://books.google.com/books?id=Ql6Jl6wKb88C&pg=PA289 |date=16 May 2005 |publisher=Cambridge University Press |isbn=978-0-521-82149-0 |page=289}}

File:Chamaesyce celastroides var. stokesii (5490591549).jpg formed by plant lice (Psyllidae), Chamaesyce celastroides var. stokesii]]

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 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 polyphages and feed on many species of plant.{{cite book |author1=Gullan, P.J. |author2=Cranston, P.S. |title=The Insects: An Outline of Entomology, 5th Edition |url=https://books.google.com/books?id=lF5hBAAAQBAJ&pg=PT790 |year=2014 |publisher=Wiley |isbn=978-1-118-84616-2 |pages=80–81, 790–}} The relationship between hemipterans and plants appears to be ancient, with piercing and sucking of plants evident in the Early Devonian period.{{cite journal |last1=Labandeira |first1=Conrad C. |title=Early History of Arthropod and Vascular Plant Associations |journal=Annual Review of Earth and Planetary Sciences |date=May 1998 |volume=26 |pages=329–377 |doi=10.1146/annurev.earth.26.1.329 |bibcode=1998AREPS..26..329L }}

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.{{cite book |last=Verne |first=Nole C. |title=Forest Ecology Research Horizons |url=https://books.google.com/books?id=WQvJiiCUGVEC&pg=PA210 |year=2007 |publisher=Nova Publishers |isbn=978-1-60021-490-5 |page=210}} 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 parthenogenetically reproducing females on a herbaceous plant.{{cite book |last=Dixon |first=A.F.G. |title=Aphid Ecology: An optimization approach |url=https://books.google.com/books?id=YrvwCAAAQBAJ&pg=PA128 |year=2012 |publisher=Springer Science & Business Media |isbn=978-94-011-5868-8 |page=128}}

File:Wilting a twig (4608641762).jpg) piercing and sucking sap from a Zinnia]]

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.{{cite book |last1=Tonkyn |first1=David W. |last2=Whitcomb |first2=Robert F. |title=Current Topics in Vector Research |editor=Harris, Kerry F. |chapter=Feeding Strategies and the Guild Concept Among Vascular Feeding Insects and Microorganisms|doi=10.1007/978-1-4612-4712-8_6 |pages=179–199 |year=1987 |isbn= 978-1-4612-9126-8 }}

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.{{cite journal| title=A phloem-sap feeder mixes phloem and xylem sap to regulate osmotic potential| author1=Pompon, Julien |author2=Quiring, Dan| author3=Goyer, Claudia| author4=Giordanengo, Philippe| author5=Pelletier, Yvan |journal=Journal of Insect Physiology| volume=57| issue=9| year=2011| pages=1317–1322| url=https://www.u-picardie.fr/PCP/data/pub/2011-Pompon%20et%20al.J%20Insect%20Physiol.pdf| doi=10.1016/j.jinsphys.2011.06.007| pmid=21726563| bibcode=2011JInsP..57.1317P | access-date=2015-08-22| archive-url=https://web.archive.org/web/20150923191653/https://www.u-picardie.fr/PCP/data/pub/2011-Pompon%20et%20al.J%20Insect%20Physiol.pdf| archive-date=2015-09-23| url-status=dead}} Xylem feeders tend to be polyphagous;{{cite journal|last1=Den|first1=Francesca F. |last2=Stewart |first2=Alan J. A. |last3=Gibson |first3=Amos |last4=Weiblen |first4=George D. |last5=Novotny |first5=Vojtech |title=Low host specificity in species-rich assemblages of xylem- and phloem-feeding herbivores (Auchenorrhyncha) in a New Guinea lowland rain forest |journal=Journal of Tropical Ecology |date=2013 |pages=467–476 |doi=10.1017/S0266467413000540 |url=http://geo.cbs.umn.edu/DemEtAl2013.pdf |volume=29|issue=6 |s2cid=12101409 }} to overcome the negative pressure of xylem requires a special cibarial pump.{{cite journal |title= Why are there no small species among xylem-sucking insects? |journal=Evolutionary Ecology |year=1997| volume=11|issue=4 | pages=419–437 |author1=Novotny, Vojtech |author2=Wilson, Michael R. |doi=10.1023/a:1018432807165|bibcode=1997EvEco..11..419N |s2cid=39222473 }}

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.{{cite journal |title=Phloem-sap feeding by animals: problems and solutions |author=Douglas, A.E.| journal=Journal of Experimental Botany| year=2006| volume=57| issue=4| pages=747–754| doi=10.1093/jxb/erj067| pmid=16449374| url=https://academic.oup.com/jxb/article-pdf/57/4/747/1487897/erj067.pdf| doi-access=free}}{{cite journal| title=Mesophyll cell-sucking herbivores (Cicadellidae: Typhlocybinae) on rainforest trees in Papua New Guinea: local and regional diversity of a taxonomically unexplored guild Ecological Entomology| year=2014| volume=39| issue=3| pages=325–333 |doi=10.1111/een.12104 |author1=Baje, Leontine |author2= Stewart, A.J.A. |author3=Novotny, Vojtech | journal=Ecological Entomology| s2cid=55083254}} 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.{{cite book |author1=Panizzi, Antônio Ricardo |author2=Parra, José R.P.|title=Insect Bioecology and Nutrition for Integrated Pest Management |url=https://books.google.com/books?id=NqzcD2r3jBYC&pg=PA108 |year=2012 |publisher=CRC Press |isbn=978-1-4398-3708-5 |page=108}} Some phloem sap feeders selectively mix phloem and xylem sap to control the osmotic potential of the liquid consumed.{{cite journal |last1=Pompon |first1=Julien |last2=Quiring |first2=Dan |last3=Goyer |first3=Claudia |last4=Giordanengo |first4=Philippe |last5=Pelletier |first5=Yvan |title=A phloem-sap feeder mixes phloem and xylem sap to regulate osmotic potential |journal=Journal of Insect Physiology |date=2011 |volume=57 |issue=9 |pages=1317–1322 |url=https://www.u-picardie.fr/PCP/data/pub/2011-Pompon%20et%20al.J%20Insect%20Physiol.pdf |doi=10.1016/j.jinsphys.2011.06.007 |pmid=21726563 |bibcode=2011JInsP..57.1317P |access-date=2015-08-22 |archive-url=https://web.archive.org/web/20150923191653/https://www.u-picardie.fr/PCP/data/pub/2011-Pompon%20et%20al.J%20Insect%20Physiol.pdf |archive-date=2015-09-23 |url-status=dead }}

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.{{cite web |title=Digestive System |url=http://bugs.bio.usyd.edu.au/learning/resources/Entomology/internalAnatomy/digestiveSystem.html |website=Entomology |publisher=University of Sydney |access-date=22 August 2015 |archive-date=7 October 2012 |archive-url=https://web.archive.org/web/20121007222727/http://bugs.bio.usyd.edu.au/learning/resources/Entomology/internalAnatomy/digestiveSystem.html |url-status=dead }} 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.{{cite web |last1=Underwood |first1=D. L. A. |title=Hemipteroids |url=http://web.csulb.edu/~dlunderw/entomology/12_13-Hemipteroids.pdf |publisher=California State University |access-date=22 August 2015 |archive-date=4 March 2016 |archive-url=https://web.archive.org/web/20160304190233/http://web.csulb.edu/~dlunderw/entomology/12_13-Hemipteroids.pdf |url-status=dead }}

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 hackleberry gall psyllid for example, causes a woody gall on the leaf petioles of the hackleberry tree it infests,{{cite web |url=http://entomology.ifas.ufl.edu/creatures/trees/hackberry_psyllid.htm |title=Hackberry petiole gall psyllid |author1=Hall, Donald W. |author2=Butler, Jerry F. |author3=Cromroy, Harvey L. |date=1 September 2014 |work=Featured Creatures |publisher=University of Florida/IFAS |access-date=12 August 2015}} and the nymph of another psyllid produces a protective lerp out of hardened honeydew.

Most other hemipterans are 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 predatory shield bug for example stabs caterpillars with its beak and sucks out the body fluids.{{cite web |url=http://www.brisbaneinsects.com/brisbane_stinkbugs/GlossyShieldBugs.htm |title=Glossy Shield Bug: Cermatulus nasalis |date=2010 |publisher=Brisbane Insects and Spiders |access-date=16 July 2015}} The saliva of predatory heteropterans contains digestive enzymes such as proteinase and phospholipase, and in some species also amylase. 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.{{cite journal |last1=Cohen |first1=Allen C. |title=Feeding Adaptations of Some Predaceous Hemiptera |url=http://insectdiets.com/wp-content/uploads/2012/07/Cohen-47.pdf | journal=Annals of the Entomological Society of America | volume=83 | issue=6 | pages=1215–1223 | date=1990 | doi=10.1093/aesa/83.6.1215}}

A few hemipterans are haematophagic ectoparasites,{{cite journal |last1=Goddard |first1=Jerome |title=Bed Bugs (Cimex lectularius) and Clinical Consequences of Their Bites |journal=JAMA |date=2009 |volume=301 |issue=13 |pages=1358–1366 |doi=10.1001/jama.2009.405 |pmid=19336711|doi-access=free }} feeding on the blood of larger animals. These include bedbugs and the triatomine kissing bugs of the assassin bug family Reduviidae, which can transmit the dangerous Chagas disease. 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.{{cite journal |doi= 10.1089/vbz.2005.5.72 |last= Poinar |first=G. |title=Triatoma dominicana sp. n. (Hemiptera: Reduviidae: Triatominae), and Trypanosoma antiquus sp. n. (Stercoraria: Trypanosomatidae), the First Fossil Evidence of a Triatomine-Trypanosomatid Vector Association |journal= Vector-Borne and Zoonotic Diseases |volume= 5|issue= 1|pages= 72–81|year= 2005 |pmid= 15815152}}

{{further|myrmecophily}}

File:Common jassid nymphs and ants02.jpgs protected by meat ants]]

Some species of ant protect and farm aphids (Sternorrhyncha) and other sap-sucking hemipterans, gathering and eating the honeydew that these hemipterans secrete. The relationship is 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.{{cite journal |last1=Ivens |first1=A. B. F. |last2=Kronauer |first2=D. J. C. |last3=Pen |first3=I. |last4=Weissing |first4=F. J. |last5=Boomsma |first5=J. J. |title=Reproduction and dispersal in an ant-associated root aphid community |journal=Molecular Ecology|date=2012 |pages=4257–69 |doi=10.1111/j.1365-294X.2012.05701.x |url=https://www.researchgate.net/publication/229163242 |volume=21 |issue=17 |pmid=22804757|bibcode=2012MolEc..21.4257I |s2cid=34429056 }} 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.{{cite book |last=Choe |first=Jae |title=Secret Lives of Ants |url=https://books.google.com/books?id=gACBQhye2wsC&pg=PT62|date=14 February 2012 |publisher=JHU Press |isbn=978-1-4214-0521-6 |pages=62–64}}

{{further|antipredator adaptation}}

File:Reduvius personatus, Masked Hunter Bug nymph camouflaged with sand grains.JPG nymph has camouflaged itself with sand grains.]]

Hemiptera form prey to predators including vertebrates, such as birds, and other invertebrates such as ladybirds.{{cite journal |last1=Evans |first1=Edward W. |title=Lady beetles as predators of insects other than Hemiptera |journal=Biological Control |date=November 2009 |volume=51 |issue=2|pages=255–267 |doi=10.1016/j.biocontrol.2009.05.011 |bibcode=2009BiolC..51..255E }}{{cite book |last1=Edmunds |first1=M. |title=Defence in Animals |url=https://archive.org/details/defenceinanimals0000edmu |url-access=registration |date=1974 |publisher=Longman |isbn=978-0-582-44132-3 |pages=[https://archive.org/details/defenceinanimals0000edmu/page/172 172], 191–194, 201, 261 and passim}} In response, hemipterans have evolved antipredator adaptations. Ranatra may feign death (thanatosis). Others such as Carpocoris purpureipennis secrete 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 Masked hunter bug camouflages itself with sand grains, using its hind legs and tarsal fan to form a double layer of grains, coarser on the outside.{{cite journal |author=Wierauch C. |year=2006 |title=Anatomy of Disguise: Camouflaging Structures in Nymphs of Some Reduviidae (Heteroptera) |journal=American Museum Novitates |volume=3542 |pages=1–18 |doi=10.1206/0003-0082(2006)3542[1:aodcsi]2.0.co;2|hdl=2246/5820 |s2cid=7894145 |url=https://www.biodiversitylibrary.org/item/280965 }} 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 cryptic to deimatic behaviour.{{cite book |last=Cott |first=Hugh B. |title=Adaptive Coloration in Animals |url=https://archive.org/details/adaptivecolorati00cott |date=1940 |publisher=Methuen |pages=[https://archive.org/details/adaptivecolorati00cott/page/375 375–376]}}{{efn|The green/red flash coloration earns the insect the name of stop and go cicada.{{cite web |title=Better IDs for E.A. Seguy Cicada Illustrations |url=http://www.cicadamania.com/cicadas/2015/03/ |access-date=24 August 2015}}}}

File:Pyrrhocoris apterus group.jpg, protect themselves from predators with bright aposematic warning coloration, and by aggregating in a group.]]

Some hemipterans such as firebugs have bold aposematic warning coloration, often red and black, which appear to deter passerine birds.{{cite book |last=Wheeler |first=Alfred George |title=Biology of the Plant Bugs (Hemiptera: Miridae): Pests, Predators, Opportunists |url=https://books.google.com/books?id=0szFXwGVlo4C&pg=PA100 |year=2001 |publisher=Cornell University Press |isbn=978-0-8014-3827-1 |pages=100ff}}{{cite journal |last1=Exnerova |first1=Alice |display-authors=etal|title=Reactions of passerine birds to aposematic and non-aposematic firebugs (Pyrrhocoris apterus; Heteroptera) |journal=Biological Journal of the Linnean Society |date=April 2003 |volume=78 |issue=4 |pages=517–525 |doi=10.1046/j.0024-4066.2002.00161.x|doi-access=free }} 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.{{cite journal |last1=Lucchi |first1=Andrea |last2=Mazzoni |first2=Emanuele |title=Wax Production in Adults of Planthoppers (Homoptera: Fulgoroidea) with Particular Reference to Metcalfa pruinosa (Flatidae) |journal=Annals of the Entomological Society of America |date=2004 |volume=97 |issue=6 |pages=1294–1298 |url=http://ag.udel.edu/delpha/2926.pdf |doi=10.1603/0013-8746(2004)097[1294:wpiaop]2.0.co;2|doi-access=free }} 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.{{cite journal|title=Structure and Function of the Malpighian Tubules, and Related Behaviors in Juvenile Cicadas: Evidence of Homology with Spittlebugs (Hemiptera: Cicadoidea & Cercopoidea)|first=Roman A. |last=Rakitov |doi=10.1078/0044-5231-00025 |journal=Zoologischer Anzeiger|volume =241|issue= 2|year=2002|pages =117–130|bibcode=2002ZooAn.241..117R }}

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.{{cite book|chapter= Maternal care in the Hemiptera: ancestry, alternatives, and current adaptive value|author1=Tallamy, Douglas W.|author2= Schaefer, Carl|pages=91–115 |publisher=Cambridge University Press|title=The Evolution of Social Behaviour in Insects and Arachnids |year=1997|editor=Jae C. Choe |editor2=Bernard J. Crespi}} In the aquatic Belostomatidae, females lay their eggs on the back of the male which guards the eggs.{{cite journal|title=Parental care and foraging ability in male water bugs (Belostoma flumineum)|author1=Crowl, T.A.|author2=Alexander Jr., J.E.|journal=Canadian Journal of Zoology|year= 1989|volume= 67|issue=2|pages=513–515|doi=10.1139/z89-074}} Protection provided by ants is common in the Auchenorrhyncha.

{{further|Insects in culture}}

Image:Icerya purchasi 1435060.jpg, a pest of citrus fruits]]

Although many species of Hemiptera are significant pests of crops and garden plants, including many species of 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.{{cite web |url=http://www.amentsoc.org/insects/fact-files/orders/ |title=Insect groups (Orders) |publisher=Amateur Entomologists' Society |access-date=16 July 2015}} They often produce copious amounts of honeydew which encourages the growth of sooty mould.{{cite web |url=https://www.rhs.org.uk/advice/profile?PID=770 |title=Sooty moulds |publisher=Royal Horticultural Society |access-date=16 July 2015}} Significant pests include the cottony cushion scale, a pest of citrus fruit trees,{{cite web |url=http://gardenbees.com/biological%20control/revolution.htm |title=Cottony cushion scale: The pest that launched a revolution in pest control methods |date=10 August 2003 |author=David L. Green |access-date=16 July 2015}} the green peach aphid and other aphids which attack crops worldwide and transmit diseases,{{cite web |url=http://entnemdept.ufl.edu/creatures/veg/aphid/green_peach_aphid.htm |title=Featured creatures |last=Capinera |first=John L. |date=October 2005 |publisher=University of Florida Department of Entomology and Nematology |access-date=16 July 2015}} and jumping plant lice which can be plant-specific and transmit diseases, as with the Asian citrus psyllid which transmits citrus greening disease.{{cite web |title=Asian citrus psyllid - Diaphorina citri Kuwayama |url=http://entnemdept.ufl.edu/creatures/citrus/acpsyllid.htm |publisher=University of Florida Department of Entomology and Nematology |access-date=3 April 2020}}

File:Spined soldier bug.webm Spined soldier bug eggs and then the recently hatched first instar bugs]]

Members of the families Reduviidae, Phymatidae and Nabidae are obligate predators. Some predatory species are used in biological pest control; these include various nabids,{{cite journal |url=http://www.entomology.wisc.edu/mbcn/kyf402.html |title=Know Your Friends: Damsel Bugs |author=Mahr, Susan |journal=Biological Control News |year=1997 |volume=IV |issue=2 |access-date=16 July 2015 |archive-date=20 April 2018 |archive-url=https://web.archive.org/web/20180420161131/http://www.entomology.wisc.edu/mbcn/kyf402.html |url-status=dead }} and even some members of families that are primarily phytophagous, such as the genus Geocoris in the family Lygaeidae.{{cite web |editor1=Weeden, Catherine R. |editor2=Shelton, Anthony M. |editor3=Hoffman, Michael P. |work=Biological Control: A Guide to Natural Enemies in North America |url=http://www.nysaes.cornell.edu/ent/biocontrol/predators/Geocoris.html |author=James Hagler |publisher=Cornell University |title=Geocoris spp. (Heteroptera: Lygaeidae): Bigeyed Bug |access-date=16 July 2015}} 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.{{cite journal |author1=Torres, Jorge Braz |author2=Boyd, David W. |year=2009 |title=Zoophytophagy in predatory Hemiptera |journal=Brazilian Archives of Biology and Technology |volume=52 |issue=5 |doi=10.1590/S1516-89132009000500018 |pages=1199–1208|doi-access=free }}

The spined soldier bug (Podisus maculiventris) sucks body fluids from several pests including the larvae of the Colorado beetle and the Mexican bean beetle.{{cite book |title=Predatory Heteroptera: their ecology and use in biological control |editor=Coll, M. |editor2=Ruberson, J.R. |year=1998 |publisher=Entomological Society of America |isbn=978-0-938522-62-1 |url=http://www.cabdirect.org/abstracts/19981105845.html;jsessionid=B3E7BAA960BF7059CA04F60707516915 }}{{Dead link|date=January 2020 |bot=InternetArchiveBot |fix-attempted=yes }}

File:Indian collecting cochineal.jpg scale insects being collected from a prickly pear in Central America. Illustration by José Antonio de Alzate y Ramírez, 1777]]

Other hemipterans have positive uses for humans, such as in the production of the dyestuff carmine (cochineal). The FDA has created guidelines for how to declare when it has been added to a product.[https://www.fda.gov/ForIndustry/ColorAdditives/GuidanceComplianceRegulatoryInformation/ucm153038.htm FDA Color Additives],"Guidance for Industry: Cochineal Extract and Carmine: Declaration by Name on the Label of All Foods and Cosmetic Products That Contain These Color Additives; Small Entity Compliance Guide". www.fda.gov. Retrieved 2016-02-22. 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.{{cite web |url=http://www.fao.org/docrep/v8879e/v8879e09.htm |title=Cochineal and Carmine |work=Major colourants and dyestuffs, mainly produced in horticultural systems |publisher=FAO |access-date=June 16, 2015}} A similar number of lac bugs are needed to make a kilogram of shellac, a brush-on colourant and wood finish.{{cite news|title=How Shellac Is Manufactured|url=http://nla.gov.au/nla.news-article55073762|access-date=17 July 2015|publisher=The Mail (Adelaide, SA : 1912 – 1954)|date=18 Dec 1937}} 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.{{cite journal |author1=Pearnchob, N. |author2=Siepmann, J. |author3=Bodmeier, R. |year=2003 |title=Pharmaceutical applications of shellac: moisture-protective and taste-masking coatings and extended-release matrix tablets |journal=Drug Development and Industrial Pharmacy |volume=29 |issue=8 |pages=925–938 |pmid=14570313 |doi=10.1081/ddc-120024188|s2cid=13150932 }}

File:Bed bug, Cimex lectularius.jpg, engorged with human blood]]

Chagas disease is a modern-day tropical disease caused by Trypanosoma cruzi and transmitted by kissing bugs, so-called because they suck human blood from around the lips while a person sleeps.{{cite web|publisher=Centers for Disease Control (CDC) |url= https://www.cdc.gov/dpdx/trypanosomiasisAmerican/ |title= American Trypanosomiasis |access-date=17 July 2015}}

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.{{cite journal |last=Goddard |first=J |author2=deShazo, R |title=Bed bugs (Cimex lectularius) and clinical consequences of their bites |journal=JAMA: The Journal of the American Medical Association |date=1 April 2009 |volume=301 |issue=13 |pages=1358–66 |pmid=19336711 |doi=10.1001/jama.2009.405|doi-access=free }}{{Cite journal| last1=Reinhardt | first1=Klaus| last2=Siva-Jothy| first2=Michael T.| title=Biology of the Bed Bugs (Cimicidae) | journal=Annual Review of Entomology| volume=52| pages=351–374|date=Jan 2007| pmid=16968204 | url=http://www.falw.vu.nl/nl/Images/siva%202006_tcm19-30750.pdf |doi=10.1146/annurev.ento.52.040306.133913 |access-date=26 May 2010 | archive-url=https://web.archive.org/web/20100705084911/http://www.falw.vu.nl/nl/Images/siva%202006_tcm19-30750.pdf| archive-date=5 July 2010}} Bed bugs 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 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.

File:deepfried cicada.jpgs, Cryptotympana atrata, in Chinese Shandong cuisine]]

Some larger hemipterans such as cicadas are used as food in Asian countries such as China,{{cite web |last1=Greenaway |first1=Twilight |url=http://www.smithsonianmag.com/arts-culture/the-best-way-to-handle-the-coming-cicada-invasion-heat-up-the-deep-fryer-19372006 |title=The Best Way to Handle the Coming Cicada Invasion? Heat Up the Deep Fryer |publisher=Smithsonian |access-date=12 July 2015}} 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.{{cite news |title=Could insects be the wonder food of the future? |author=Anthes, Emily |url=http://www.bbc.com/future/story/20141014-time-to-put-bugs-on-the-menu |newspaper=BBC |date=14 October 2014 |access-date=17 July 2015}} At least nine species of Hemiptera are eaten worldwide.{{cite web | url=http://www.fao.org/docrep/018/i3253e/i3253e00.htm | title=Future Prospects for Food and Feed Security | access-date=13 April 2016 | archive-date=4 April 2016 | archive-url=https://web.archive.org/web/20160404091437/http://www.fao.org/docrep/018/i3253e/i3253e00.htm | url-status=dead }}

Cicadas have featured in literature since the time of Homer's 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; 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".{{cite book | author=Myers, J. G. |title=Insect Singers | publisher=G. Routledge and Sons| date=1929 |url=http://entnemdept.ufl.edu/walker/buzz/c700lm29sec01.pdf}}

{{further|Cicada (mythology)}}

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.{{cite web |title=Cicada |url=https://www.britannica.com/animal/cicada |publisher=Britannica |access-date=12 July 2015}}

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.{{cite journal |last1=Cunha |first1=Erlane Jose |last2=Montag |first2=Luciano |last3=Juen |first3=Leandro |title=Oil palm crops effects on environmental integrity of Amazonian streams and Heteropteran (Hemiptera) species diversity |journal=Ecological Indicators |date=2015 |volume=52 |pages=422–429 |doi=10.1016/j.ecolind.2014.12.024|bibcode=2015EcInd..52..422C }} 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.{{cite journal |last1=Baker |first1=Mitchell B. |last2=Venugopal |first2=P. Dilip |last3=Lamp |first3=William O. |title=Climate Change and Phenology: Empoasca fabae (Hemiptera: Cicadellidae) Migration and Severity of Impact |journal=PLOS ONE |date=2015|volume=10 |issue=5 |page=e0124915 |doi=10.1371/journal.pone.0124915 |pmid=25970705 |pmc=4430490|bibcode=2015PLoSO..1024915B |doi-access=free }}

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• [http://tolweb.org/Hemiptera/8239 Cladogram of Hemiptera at Tree of Life Project] {{Webarchive|url=https://web.archive.org/web/20200120044901/http://tolweb.org/Hemiptera/8239 |date=20 January 2020 }}

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{{Hemiptera}}

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Category:Insect orders

Category:Extant Pennsylvanian first appearances

Category:Taxa named by Carl Linnaeus

Category:Condylognatha