Editing Phasmatodea (section)

==Behavior==
[[File:Poke It Stick.ogv|thumb|Video of a walking phasmid]]
Stick insects, like [[praying mantis]]es, show rocking behavior in which the insect makes rhythmic, repetitive, side-to-side movements. The common interpretation of this behavior's function is it enhances [[crypsis]] by mimicking vegetation moving in the wind. These movements may also be important in allowing the insects to discriminate objects from the background by relative motion. Rocking movements by these generally sedentary insects may replace flying or running as a source of relative motion to help them discern objects in the foreground.<ref>O'Dea, JD. Eine zusatzliche oder alternative Funktion der 'kryptischen' Schaukelbewegung bei Gottesanbeterinnen und Stabschrecken (Mantodea, Phasmatodea). Entomologische Zeitschrift, 101, Nr. 1/2, 15 Januar 1991, 25-27.</ref>

Mating behavior in Phasmatodea is impressive because of the extraordinarily long duration of some pairings. A record among insects, the stick insect ''[[Necroscia sparaxes]]'', found in India, is sometimes coupled for 79 days at a time. It is not uncommon for this species to assume the [[mating posture]] for days or weeks on end, and among some species (''[[Diapheromera veliei]]'' and ''[[Diapheromera covilleae|D. covilleae]]''), pairing can last three to 136 hours in captivity.<ref name="siv1980">{{cite journal| last=Sivinski| first=John| title=Effects of Mating on Predation in the Stick Insect ''Diapheromera veliei'' Walsh (Phasmatodea: Heteronemiidae)| journal=Annals of the Entomological Society of America| year=1980| volume=73 |issue=5 |doi=10.1093/aesa/73.5.553 |pages=553–556}}</ref>

Overt displays of aggression between males over mates suggests that extended pairing may have [[evolved]] to guard females from [[sperm competition]]. Fighting between competing males has been observed in the species ''D. veiliei'' and ''D. covilleae''.<ref name="siv1978">{{cite journal|last=Sivinski|first=John|title=Intersexual Aggression in the Stick Insects ''Diapheromera veliei'' and ''D. covilleae'' and Sexual Dimorphism in the Phasmatodea| journal=Psyche: A Journal of Entomology| year=1978| volume=85| issue=4 |doi=10.1155/1978/35784 |pages=395–403|doi-access=free}}</ref> During these encounters, the approach of a challenger causes the existing mate to manipulate the female's abdomen, which he has clasped by means of the clasping organ, or vomer, down upon itself to block the site of attachment. Occasionally, the consort will strike out at the competitor with the mid femora, which are equipped with an enlarged and hooked spine in both sexes that can draw the blood of the opponent when they are flexed against the body to puncture the [[integument]].<ref name="siv1978" /> Usually, a strong hold on the female's abdomen and blows to the intruder are enough to deter the unwanted competition, but occasionally the competitor has been observed to employ a sneaky tactic to [[inseminate]] the female. While the first mate is engaged in feeding and is forced to vacate the [[Anatomical terms of location#Dorsal and ventral|dorsal]] position, the intruder can clasp the female's abdomen and insert his [[genitalia]]. If he is discovered, the males will enter into combat wherein they lean backward, both clasped to the female's abdomen, and freely suspended, engage in rapid, sweeping blows with their forelegs in a manner similar to [[boxing]]. Usually, when the intruder gains attachment to the female's abdomen, these conflicts result in the displacement of the original mate.<ref name="siv1978" />

[[File:Indische Stabschrecke auf einem Himbeerblatt im Terrarium.jpg|thumb|upright|''[[Carausius morosus]]'' is often kept as a pet by schools and individuals.]]

Lengthy pairings have also been described in terms of a defensive alliance. When cleaved together, the pair is more unwieldy for predators to handle. Also, the chemical defenses (secretions, reflex bleeding, regurgitation) of the individual stick insect are enhanced when two are paired. Females survive attacks by predators significantly better when pairing, largely because the dorsal position of the male functions well as a shield. This could indicate that manipulation by females is taking place: if females accept [[ejaculate]] at a slow rate, for instance, the males are forced to remain [[copulation (zoology)|''in copulo'']] for longer and the female's chances of survival are enhanced. Also, evolution could have simply favored males that remained attached to their females longer, since females are often less abundant than males and represent a valuable prize, so for the lucky male, even the sacrifice of his own life to preserve his [[offspring]] with the female may be worthwhile. [[Sexual dimorphism]] in the species, where females are usually significantly larger than the males, may have evolved due to the fitness advantage accrued to males that can remain attached to the female, thereby blocking competitors, without severely impeding her movement.<ref name="siv1980" />

Certain Phasmatodea, such as ''Anisomorpha buprestoides'', sometimes form aggregations. These insects have been observed to congregate during the day in a concealed location, going their separate ways at nightfall to forage, and returning to their refuge before dawn. Such behavior has been little studied, and how the insects find their way back is unknown.<ref name=Costa/>