Editing Grasshopper (section)

==Biology==

===Diet and digestion===
[[File:Grasshopper mouth anatomy.svg|thumb|upright=1.35|Structure of mouthparts]]
{{further|Digestive system of insects}}

Most grasshoppers are [[polyphagous]], eating vegetation from multiple plant sources,<ref>{{cite web |url=http://www.desertmuseum.org/books/nhsd_grasshopper_new.php |title=Grasshoppers |author=Davidowitz, Goggy |publisher=Arizona-Sonora Desert Museum |access-date=4 May 2015 |url-status=dead |archive-url=https://web.archive.org/web/20150507144753/http://www.desertmuseum.org/books/nhsd_grasshopper_new.php |archive-date=7 May 2015 }}</ref> but some are [[omnivorous]] and also eat animal tissue and animal faeces.<ref>{{cite journal |last1=O'Neill |first1=Kevin M. |last2=Woods |first2=Stephen A. |last3=Streett |first3=Douglas A. |title=Grasshopper (Orthoptera: Acrididae) Foraging on Grasshopper Feces: Observational and Rubidium-Labeling Studies |journal=Environmental Entomology |date=1 December 1997 |volume=26 |issue=6 |pages=1224–1231 |doi=10.1093/ee/26.6.1224 |url=https://academic.oup.com/ee/article/26/6/1224/2464391|url-access=subscription }}</ref> In general their preference is for grasses, including many [[cereal]]s grown as crops.<ref>{{cite journal |title= Grasshopper (Orthoptera: Acrididae) Foraging on Grasshopper Feces: Observational and Rubidium-Labeling Studies |author1=O'Neill, Kevin M. |author2=Woods, Stephen A. |author3=Streett, Douglas A. |journal= Environmental Entomology |volume=26 |issue=6 |year=1997 |pages=1224–1231 |doi=10.1093/ee/26.6.1224}}</ref> The digestive system is typical of insects, with Malpighian tubules discharging into the midgut. Carbohydrates are digested mainly in the crop, while proteins are digested in the ceca of the midgut. Saliva is abundant but largely free of enzymes, helping to move food and Malpighian secretions along the gut. Some grasshoppers possess [[cellulase]], which by softening plant cell walls makes plant cell contents accessible to other digestive enzymes.<ref>{{cite book |last=Gilbert |first=Lawrence Irwin |title=Insect Molecular Biology and Biochemistry |url=https://books.google.com/books?id=H9iXwIC_l3cC&pg=PA399 |year=2012 |publisher=Academic Press |isbn=978-0-12-384747-8 |page=399 |url-status=live |archive-url=https://web.archive.org/web/20171127023308/https://books.google.com/books?id=H9iXwIC_l3cC&pg=PA399 |archive-date=27 November 2017 }}</ref> Grasshoppers can also be [[cannibalism|cannibalistic]] when swarming.<ref>{{Cite book |last=Sinclair |first=David A. |authorlink=David A. Sinclair |url=https://www.worldcat.org/oclc/1088652276 |title=Lifespan |date=2019 |others=Matthew D. LaPlante, Catherine Delphia |isbn=978-1-5011-9197-8 |edition=1st |location=New York |oclc=1088652276 |page=99}}</ref><ref>{{Cite web |date=2008-05-08 |title=March of the locusts – individuals start moving to avoid cannibals |url=https://www.nationalgeographic.com/science/article/march-of-the-locusts-individuals-start-moving-to-avoid-cannibals |archive-url=https://web.archive.org/web/20210521123320/https://www.nationalgeographic.com/science/article/march-of-the-locusts-individuals-start-moving-to-avoid-cannibals |url-status=dead |archive-date=21 May 2021 |first=Ed |last=Yong |website=nationalgeographic.com|language=en}}</ref><ref>{{Cite web |title=From solo to sociable—how locusts try to avoid cannibalism |url=https://phys.org/news/2012-08-solo-sociablehow-locusts-cannibalism.html |date=2012-08-29 |website=phys.org |language=en}}</ref>

[[File:Grasshopper eating leaf.jpg|thumb|none|alt=A differential grasshopper eating the leaf of a climbing pea plant|A [[differential grasshopper]] eating the leaf of a [[pea|climbing pea]] plant. [[Cellulase]] in its [[Gastrointestinal tract|digestive tract]] allows it to digest [[cellulose]] in the [[cell wall]]s of plants.]]

===Sensory organs===
[[File:Anacridium aegyptium - 01.jpg|thumb|Frontal view of Egyptian locust (''[[Anacridium aegyptium]]'') showing the [[compound eye]]s, tiny [[Simple eye in invertebrates|ocelli]] and numerous [[seta]]e]]
Grasshoppers have a typical insect nervous system, and have an extensive set of external sense organs. On the side of the head are a pair of large [[compound eyes]] which give a broad field of vision and can detect movement, shape, colour and distance. There are also three simple eyes ([[ocelli]]) on the forehead which can detect light intensity, a pair of antennae containing olfactory (smell) and touch receptors, and mouthparts containing gustatory (taste) receptors.<ref name=Ruppert>{{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=735–737 }}</ref> At the front end of the abdomen there is a pair of tympanal organs for sound reception. There are numerous fine hairs ([[setae]]) covering the whole body that act as mechanoreceptors (touch and wind sensors), and these are most dense on the antennae, the [[palp]]s (part of the mouth), and on the cerci at the tip of the abdomen.<ref name=Chapman>Chapman, 2013. pp. 745–755</ref> There are special receptors ([[campaniform sensilla]]e) embedded in the cuticle of the legs that sense pressure and cuticle distortion.<ref>Chapman, 2013. p. 163</ref> There are internal "chordotonal" sense organs specialized to detect position and movement about the joints of the exoskeleton. The receptors convey information to the central nervous system through sensory neurons, and most of these have their cell bodies located in the periphery near the receptor site itself.<ref name=Chapman/>

===Circulation and respiration===
{{further|Insect morphology#Circulatory system|Respiratory system of insects}}
Like other insects, grasshoppers have an [[open circulatory system]] and their body cavities are filled with [[haemolymph]]. A heart-like structure in the upper part of the abdomen pumps the fluid to the head from where it percolates past the tissues and organs on its way back to the abdomen. This system circulates nutrients throughout the body and carries [[metabolic waste]]s to be excreted into the gut. Other functions of the haemolymph include wound healing, heat transfer and the provision of hydrostatic pressure, but the circulatory system is not involved in gaseous exchange.<ref>{{cite web |url=https://projects.ncsu.edu/cals/course/ent425/library/tutorials/internal_anatomy/circulatory.html |title=Circulatory system |author=Meyer, John R. |date=8 April 2009 |work=General Entomology |publisher=NC State University |access-date=12 April 2015 |url-status=live |archive-url=https://web.archive.org/web/20170103003933/https://projects.ncsu.edu/cals/course/ent425/library/tutorials/internal_anatomy/circulatory.html |archive-date=3 January 2017 }}</ref> Respiration is performed using [[Trachea#Invertebrates|trachea]]e, air-filled tubes, which open at the surfaces of the thorax and abdomen through pairs of valved [[Spiracle (arthropods)|spiracle]]s. Larger insects may need to actively ventilate their bodies by opening some spiracles while others remain closed, using abdominal muscles to expand and contract the body and pump air through the system.<ref>{{cite web |url=https://projects.ncsu.edu/cals/course/ent425/library/tutorials/internal_anatomy/respiratory.html |title=Insect physiology: Respiratory system |author=Meyer, John R. |date=1 November 2006 |work=General Entomology |publisher=NC State University |access-date=12 April 2015 |url-status=live |archive-url=https://web.archive.org/web/20170103003044/https://projects.ncsu.edu/cals/course/ent425/library/tutorials/internal_anatomy/respiratory.html |archive-date=3 January 2017 }}</ref>

=== Jumping ===

Grasshoppers jump by extending their large back legs and pushing against the substrate (the ground, a twig, a blade of grass or whatever else they are standing on); the reaction force propels them into the air.<ref>{{cite web |last1=Heitler |first1=W.J. |title=How Grasshoppers Jump |url=http://www.st-andrews.ac.uk/~wjh/jumping/ |publisher=University of St Andrews |access-date=3 April 2015 |date=January 2007 |url-status=live |archive-url=https://web.archive.org/web/20150924123105/http://www.st-andrews.ac.uk/~wjh/jumping/ |archive-date=24 September 2015 }}</ref> A large grasshopper, such as a locust, can jump about a metre (20 body lengths<!--5 cm body=1/20 m-->) without using its wings; the acceleration peaks at about 20&nbsp;g.<ref>{{cite web |last1=Heitler |first1=W.J. |title=Performance |url=http://www.st-andrews.ac.uk/~wjh/jumping/perform.htm |publisher=University of St Andrews |access-date=13 April 2015 |date=January 2007 |url-status=live |archive-url=https://web.archive.org/web/20150319133858/http://www.st-andrews.ac.uk/~wjh/jumping/perform.htm |archive-date=19 March 2015 }}</ref>

They jump for several reasons; to escape from a predator, to launch themselves into flight, or simply to move from place to place. For the escape jump in particular there is strong selective pressure to maximize take-off velocity, since this determines the range. This means that the legs must thrust against the ground with both high force and a high velocity of movement. A fundamental property of [[muscle contraction#Force-length and force-velocity relationships|muscle]] is that it cannot contract with high force and high velocity at the same time. Grasshoppers overcome this by using a [[catapult]] mechanism to amplify the [[Power (physics)#Mechanical power|mechanical power]] produced by their muscles.<ref>{{cite web |last1=Heitler |first1=W.J. |title=Energy and Power |url=http://www.st-andrews.ac.uk/~wjh/jumping/power.htm |publisher=University of St Andrews |access-date=5 May 2015 |date=January 2007 |url-status=live |archive-url=https://web.archive.org/web/20141118101313/http://www.st-andrews.ac.uk/~wjh/jumping/power.htm |archive-date=18 November 2014 }}</ref>

The jump is a three-stage process.<ref>{{Cite journal | doi = 10.1007/BF00219055|pmid=7707268| title = Motor patterns during kicking movements in the locust| journal=Journal of Comparative Physiology A| volume = 176| issue = 3 |pages=289–305| year=1995| last1=Burrows | first1 = M.|s2cid=21759140}}</ref> First, the grasshopper fully flexes the lower part of the leg (tibia) against the upper part (femur) by activating the flexor tibiae muscle (the back legs of the grasshopper in the top photograph are in this preparatory position). Second, there is a period of co-contraction in which force builds up in the large, [[Pennate muscle|pennate]] extensor tibiae muscle, but the tibia is kept flexed by the simultaneous contraction of the flexor tibiae muscle. The extensor muscle is much stronger than the flexor muscle, but the latter is aided by specialisations in the joint that give it a large effective mechanical advantage over the former when the tibia is fully flexed.<ref>{{cite journal |author= Heitler, W.J. |year= 1977 |title= The locust jump III. Structural specialisations of the metathoracic tibiae |journal= Journal of Experimental Biology |volume= 67 |pages= 29–36 |doi= 10.1242/jeb.67.1.29 |url= http://jeb.biologists.org/content/jexbio/67/1/29.full.pdf |url-status= live |archive-url= https://web.archive.org/web/20161019094114/http://jeb.biologists.org/content/jexbio/67/1/29.full.pdf |archive-date= 19 October 2016 }}</ref> Co-contraction can last for up to half a second, and during this period the extensor muscle shortens and stores elastic strain energy by distorting stiff cuticular structures in the leg.<ref>{{Cite journal | pmid=1159370 | year=1975 | last1=Bennet-Clark | first1=H.C. | title=The energetics of the jump of the locust ''Schistocerca gregaria'' | journal=The Journal of Experimental Biology | volume=63 | issue=1 | pages=53–83 | doi=10.1242/jeb.63.1.53 | url=http://jeb.biologists.org/content/63/1/53.1.long | url-status=live | archive-url=https://web.archive.org/web/20170103003849/http://jeb.biologists.org/content/63/1/53.1.long | archive-date=3 January 2017 | url-access=subscription }}</ref> The extensor muscle contraction is quite slow (almost isometric), which allows it to develop high force (up to 14&nbsp;N in the desert locust), but because it is slow only low power is needed. The third stage of the jump is the trigger relaxation of the flexor muscle, which releases the tibia from the flexed position. The subsequent rapid tibial extension is driven mainly by the relaxation of the elastic structures, rather than by further shortening of the extensor muscle. In this way the stiff cuticle acts like the elastic of a [[catapult]], or the bow of a bow-and-arrow. Energy is put into the store at low power by slow but strong muscle contraction, and retrieved from the store at high power by rapid relaxation of the mechanical elastic structures.<ref>{{cite book |author=Biewener, Andrew A. |title=Animal Locomotion |url=https://books.google.com/books?id=yMaN9pk8QJAC&pg=PA172 |year=2003 |publisher=Oxford University Press |isbn=978-0-19-850022-3 |pages=172–175 |url-status=live |archive-url=https://web.archive.org/web/20171127023307/https://books.google.com/books?id=yMaN9pk8QJAC&pg=PA172 |archive-date=27 November 2017 }}</ref>

===Stridulation===
{{Listen|filename=Grasshoppers.ogg|title=Grasshopper stridulation|description=Several unidentified grasshoppers stridulating}}
Male grasshoppers spend much of the day [[stridulation|stridulating]], singing more actively under optimal conditions and being more subdued when conditions are adverse; females also stridulate, but their efforts are insignificant when compared to the males. Late-stage male nymphs can sometimes be seen making stridulatory movements, although they lack the equipment to make sounds, demonstrating the importance of this behavioural trait. The songs are a means of communication; the male stridulation seems to express reproductive maturity, the desire for social cohesion and individual well-being. Social cohesion becomes necessary among grasshoppers because of their ability to jump or fly large distances, and the song can serve to limit dispersal and guide others to favourable habitat. The generalised song can vary in phraseology and intensity, and is modified in the presence of a rival male, and changes again to a courtship song when a female is nearby.<ref name=AES>{{cite journal |author=Brangham, A.N. |year=1960 |title=Communication among social insects |journal=Bulletin of the Amateur Entomologists' Society |volume=19 |pages=66–68 |url=https://archive.org/stream/bulletinofamateu1920amat#page/n113/mode/2up }}</ref> In male grasshoppers of the family Pneumoridae, the enlarged abdomen amplifies stridulation.<ref name="Donelson"/>

===Life cycle===
[[File:Grasshoppermetasnodgrass.svg|thumb|upright=0.6|Six stages (instars) of development, from newly hatched nymph to fully winged adult]]
[[File:Two eastern Lubber grasshopers (Romalea microptera), mating.jpg|thumb|left|''[[Romalea microptera]]'' grasshoppers: female (larger) is laying eggs, with male in attendance.]]
In most grasshopper species, conflicts between males over females rarely escalate beyond ritualistic displays. Some exceptions include the chameleon grasshopper (''[[Kosciuscola|Kosciuscola tristis]]''), where males may fight on top of ovipositing females; engaging in leg grappling, biting, kicking and mounting.<ref>{{cite journal|author1=Umbers, K. |author2=Tatarnic, N. |author3=Holwell, G. |author4=Herberstein, M. |year=2012|title=Ferocious Fighting between Male Grasshoppers |journal=PLOS ONE |volume=7 |issue=11 |page=e49600 |doi=10.1371/journal.pone.0049600 |doi-access=free |pmid=23166725 |pmc=3498212|bibcode=2012PLoSO...749600U }}</ref>

Female grasshoppers of the species ''[[Chorthippus biguttulus]]'' appear to be able to integrate information from male calling songs.<ref name = Clemens2014>Clemens J, Krämer S, Ronacher B. Asymmetrical integration of sensory information during mating decisions in grasshoppers. Proc Natl Acad Sci U S A. 2014 Nov 18;111(46):16562-7. doi: 10.1073/pnas.1412741111. Epub 2014 Nov 3. PMID: 25368152; PMCID: PMC4246278.</ref>  An unattractive song subunit far outweighs an attractive song subunit, and this asymmetrical integration is consistent with theories of [[sexual selection]] because it helps females avoid potentially costly interaction with unsuitable mating partners if the song belongs to another species or indicates a low-quality male.<ref name = Clemens2014/>

The newly emerged female grasshopper has a preoviposition period of a week or two while she increases in weight and her eggs mature. After mating, the female of most species digs a hole with her [[ovipositor]] and lays a batch of eggs in a pod in the ground near food plants, generally in the summer. After laying the eggs, she covers the hole with soil and litter.<ref name=Pfadt1to8/> Some, like the semi-aquatic ''[[Cornops aquaticum]]'', deposit the pod directly into plant tissue.<ref>{{cite journal |author1=Hill, M.P. |author2=Oberholzer, I.G. |year=2000 |title=Host specificity of the grasshopper, ''Cornops aquaticum'', a natural enemy of water hyacinth |journal=Proceedings of the X International Symposium on Biological Control of Weeds |editor=Spencer, Neal R. |publisher=Montana State University |pages=349–356 |url=http://www.invasive.org/publications/xsymposium/proceed/05pg349.pdf |url-status=live |archive-url=https://web.archive.org/web/20161220175939/http://www.invasive.org/publications/xsymposium/proceed/05pg349.pdf |archive-date=20 December 2016 }}</ref> The eggs in the pod are glued together with a froth in some species. After a few weeks of development, the eggs of most species in temperate climates go into [[diapause]], and pass the winter in this state. Diapause is broken by a sufficiently low ground temperature, with development resuming as soon as the ground warms above a certain threshold temperature. The embryos in a pod generally all hatch out within a few minutes of each other. They soon shed their membranes and their exoskeletons harden. These first [[instar]] nymphs can then jump away from predators.<ref name=UW>
Pfadt, 1994. pp. 11–16. [http://www.uwyo.edu/entomology/grasshoppers/ghlcycle.htm Diagrams] {{Webarchive|url=https://web.archive.org/web/20150402110127/http://www.uwyo.edu/entomology/grasshoppers/ghlcycle.htm |date=2 April 2015 }} 
</ref>

<!--[[File:Grasshopper moult 2015-08-04.jpg|thumb|upright=0.6|Abandoned moult]] no room for this at the moment-->
Grasshoppers undergo [[incomplete metamorphosis]]: they [[ecdysis|repeatedly moult]], each instar becoming larger and more like an adult, with the wing-buds increasing in size at each stage. The number of instars varies between species but is often six. After the final moult, the wings are inflated and become fully functional. The migratory grasshopper, ''[[Melanoplus sanguinipes]]'', spends about 25 to 30 days as a nymph, depending on sex and temperature, and lives for about 51 days as an adult.<ref name=UW/>

===Swarming===
{{main|Locust}}
[[File:CSIRO ScienceImage 7007 Plague locusts on the move.jpg|thumb|left|upright=1.2|Millions of [[Australian plague locust|plague locusts]] on the move in Australia]]

Locusts are the swarming phase of certain species of short-horned grasshoppers in the family Acrididae. Swarming behaviour is a response to overcrowding. Increased tactile stimulation of the hind legs causes an increase in levels of [[serotonin]].<ref>{{cite news |url=http://news.bbc.co.uk/2/hi/science/nature/7858996.stm |work=BBC News |author=Morgan, James |title=Locust swarms 'high' on serotonin |date=29 January 2009 |access-date=31 March 2015 |url-status=live |archive-url = https://web.archive.org/web/20131010043157/http://news.bbc.co.uk/2/hi/science/nature/7858996.stm|archive-date = 10 October 2013}}</ref> This causes the grasshopper to change colour, feed more and breed faster. The transformation of a solitary individual into a swarming one is induced by several contacts per minute over a short period.<ref>{{cite journal |author1=Rogers, Stephen M. |author2=Matheson, Thomas |author3=Despland, Emma |author4=Dodgson, Timothy |author5=Burrows, Malcolm |author6=Simpson, Stephen J. |year=2003 |title=Mechanosensory-induced behavioral gregarization in the desert locust ''Schistocerca gregaria'' |journal=[[Journal of Experimental Biology]] |volume=206 |issue=22 |pages=3991–4002 |doi=10.1242/jeb.00648 |pmid=14555739 |s2cid=10665260 |url=http://jeb.biologists.org/content/jexbio/206/22/3991.full.pdf |url-status=live |archive-url=https://web.archive.org/web/20160924005950/http://jeb.biologists.org/content/jexbio/206/22/3991.full.pdf |archive-date=24 September 2016 |doi-access=free }}</ref>

Following this transformation, under suitable conditions dense nomadic bands of flightless nymphs known as "hoppers" can occur, producing [[pheromone]]s which attract the insects to each other. With several generations in a year, the locust population can build up from localised groups into vast accumulations of flying insects known as plagues, devouring all the vegetation they encounter. The [[Albert's swarm|largest recorded locust swarm]] was one formed by the now-extinct [[Rocky Mountain locust]] in 1875; the swarm was {{convert|1800|mi}} long and {{convert|110|mi}} wide,<ref>{{cite news |title=Looking Back at the Days of the Locust |author=Yoon, Carol Kaesuk |url=https://www.nytimes.com/2002/04/23/science/looking-back-at-the-days-of-the-locust.html |newspaper=New York Times |date=23 April 2002 |access-date=31 March 2015 |url-status=live |archive-url=https://web.archive.org/web/20150403092454/http://www.nytimes.com/2002/04/23/science/looking-back-at-the-days-of-the-locust.html |archive-date=3 April 2015 }}</ref> and one estimate puts the number of locusts involved at 3.5 trillion.<ref name=Lockwood>{{cite book|last=Lockwood |first=Jeffrey A. |title=Locust: the Devastating Rise and Mysterious Disappearance of the Insect that Shaped the American Frontier |year=2004 |publisher=Basic Books |isbn=0-7382-0894-9 |page=21 |edition=1st}}ffol</ref> An adult [[desert locust]] can eat about {{convert|2|g|1|abbr=on}} of plant material each day, so the billions of insects in a large swarm can be very destructive, stripping all the foliage from plants in an affected area and consuming stems, flowers, fruits, seeds and bark.<ref name=Capinera1181/>