Editing Swarm behaviour (section)

====Locusts====
{{See also|Marching locusts}}
[[File:Schwarm Wanderheuschrecke.jpg|thumb|upright|A 19th century depiction of a swarm of [[desert locust]]s]]

[[Locust]]s are the swarming phase of the short-horned [[grasshopper]]s of the family [[Acrididae]]. Some species can breed rapidly under suitable conditions and subsequently become gregarious and migratory. They form bands as [[nymph (biology)|nymphs]] and swarms as adults—both of which can travel great distances, rapidly stripping fields and greatly [[pest (organism)|damaging crops]]. The largest swarms can cover hundreds of square miles and contain billions of locusts. A locust can eat its own weight (about 2&nbsp;grams) in plants every day. That means one million locusts can eat more than one tonne of food each day, and the largest swarms can consume over 100,000 [[tonne]]s each day.<ref>[https://web.archive.org/web/20070625102824/http://animals.nationalgeographic.com/animals/bugs/locust.html Locust ''Locustidae''] ''National Geographic''. Retrieved 12 December 2010.</ref>

Swarming in locusts has been found to be associated with increased levels of [[serotonin]] which causes the locust to change colour, eat much more, become mutually attracted, and breed much more easily. Researchers propose that swarming behaviour is a response to overcrowding and studies have shown that increased tactile stimulation of the hind legs or, in some species, simply encountering other individuals causes an increase in levels of serotonin. The transformation of the locust to the swarming variety can be induced by several contacts per minute over a four-hour period.<ref>{{cite news |url=http://news.bbc.co.uk/2/hi/science/nature/7858996.stm|title=Locust swarms 'high' on serotonin|date=29 January 2009|via=BBC}}</ref><ref>{{cite journal |doi=10.1242/jeb.00648 |vauthors=Rogers SM, Matheson T, Despland E, Dodgson T, Burrows M, Simpson SJ |date= November 2003|title=Mechanosensory-induced behavioural gregarization in the desert locust ''Schistocerca gregaria'' |journal=J. Exp. Biol. |volume=206 |issue=Pt 22 |pages=3991–4002 |pmid=14555739|doi-access=free |bibcode=2003JExpB.206.3991R }}</ref><ref>{{cite journal |doi=10.1126/science.1169280 |last=Stevenson |first=PA |title=The Key to Pandora's Box |journal=Science |volume=323 |issue=5914 |pages=594–5 |year=2009 |pmid=19179520|s2cid=39306643 }}</ref><ref>[https://www.newscientist.com/article/dn16505-blocking-happiness-chemical-may-prevent-locust-plagues.html Blocking 'happiness' chemical may prevent locust plagues], [[New Scientist]], 2009-01-29, accessed 2009-01-31</ref> Notably, an innate predisposition to aggregate has been found in hatchlings of the desert locust, ''[[Schistocerca gregaria]]'', independent of their parental phase.<ref>{{cite journal |doi= 10.1111/j.1744-7917.2012.01518.x |author1=Moshe Guershon |author2=Amir Ayali |date= May 2012 |title=Innate phase behavior in the desert locust, ''Schistocerca gregaria'' |journal= Insect Science |volume=19 |issue=6 |pages=649–656|s2cid=83412818 |doi-access=free |bibcode=2012InsSc..19..649G }}</ref>

An individual locust's response to a loss of alignment in the group appears to increase the randomness of its motion, until an aligned state is again achieved. This noise-induced alignment appears to be an intrinsic characteristic of collective coherent motion.<ref>{{cite journal |doi=10.1073/pnas.0811195106 |last1=Yates |first1=CA |last2=Erban |first2=R |last3=Escudero |first3=C |last4=Couzin |first4=ID |last5= Buhl |first5=J |last6=Kevrekidis |first6=IG |last7=Maini |first7=PK |last8=Sumpter |first8=DJ |title=Inherent noise can facilitate coherence in collective swarm motion |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=106 |issue=14 |pages=5464–9 |year=2009 |pmid=19336580 |pmc=2667078|bibcode= 2009PNAS..106.5464Y|doi-access=free }}</ref>