Editing Halteres (section)

===Convergent evolution===

Though no other structure with entirely the same function and morphology as halteres has been observed in nature, they have evolved at least twice in the class [[Insecta]], once in the order [[fly|Diptera]] and again in [[Strepsiptera]]. Another structure in the class Insecta also exists whose primary function is not the same as halteres, but that additionally serves a similar balancing function. This occurs in the order [[Lepidoptera]] and refers to the antennae of moths and butterflies.<ref name="Sane 2007" />

[[File:Strepsiptera.png|300px|thumb|right|Strepsipteran halteres: teardrop-shaped structures located between the fore and mid legs (indicated by red arrows)]]

====Strepsipteran haltere====

[[Strepsiptera]]ns are a unique group of insects with major sexual dimorphism. The females spend their entire lives in a grub-like state, [[parasitism|parasitizing]] larger insects. The only time they ever come out of their host insect is to extend their fused heads and [[thorax|thoraces]] for males to notice. The males are also parasites, but they eventually will leave their [[host (biology)|host]] to seek their female counterparts. Because of this, they still retain the ability to fly. Male strepsipterans uniquely possess two hindwings, while their forewings have taken on the club-like form of halteres.<ref>{{cite journal|last1=Proffitt|first1=F.|title=PARASITOLOGY: Twisted Parasites From|journal=Science|date=21 January 2005|volume=307|issue=5708|pages=343|doi=10.1126/science.307.5708.343|pmid=15661988|s2cid=28071190 }}</ref> Though strepsipterans are very difficult to locate and are additionally rather short-lived, Pix ''et al.'' (1993) confirmed that the specialized forewings that male Strepsiptera possess perform the same function as dipteran halteres. Rotational movements of the body combined with the oscillating halteres produce Coriolis forces that can be detected by fields of mechanosensors (campaniform sensilla) located at the base of the halteres. Using functional morphology and behavior studies, Pix ''et al.'' showed that these sensors then transmit body position information to the head and abdomen to produce compensatory movements.<ref name="Pix 1993" /> For simplicity, the remainder of this article will refer only to dipteran halteres.

====Lepidopteran antennae====

Certain [[lepidoptera]]ns (moths and butterflies) exhibit small amplitude oscillation of their [[antenna (biology)|antennae]] at constant angles during flight.<ref name="Sane 2007">{{cite journal|last1=Sane|first1=SP|last2=Dieudonné|first2=A|last3=Willis|first3=MA|last4=Daniel|first4=TL|title=Antennal mechanosensors mediate flight control in moths |journal=Science|date=9 February 2007|volume=315|issue=5813|pages=863–6|pmid=17290001|doi=10.1126/science.1133598|bibcode=2007Sci...315..863S|s2cid=2429129}}</ref> Antennal movements in lepidopterans were originally hypothesized to aid in wind or gravity perception.<ref>{{cite journal|last1=Niehaus|first1=Monika|title=Flight and flight control by the antennae in the Small Tortoiseshell (Aglais urticae L., Lepidoptera)|journal=Journal of Comparative Physiology A|date=1981|volume=145|issue=2|pages=257–264|doi=10.1007/BF00605038|s2cid=45437698}}</ref> A study performed using the hawk moth, ''Manduca sexta'', confirmed that these tiny, antennal oscillations were actually contributing to body rotation sensation.<ref name="Sane 2007" />

Sane ''et al.'' (2007) determined that antennae were responsible for flight stabilization in hawk moths by removing the long part of the antenna (the flagellum), then reattaching it to determine its influence on flight performance. When the flagella were removed, the moths were no longer able to maintain stable flight. After reattachment of the flagella, flight performance was restored. The source of this difference was determined to be mechanosensory. There are two sets of mechanosensory organs located at the base of the lepidopteran antenna, Böhm's bristles and the Johnston organ. These fields of receptors respond to different directions of antennal movements. Antennae are also capable of sensing odor, humidity, and temperature. Sane ''et al.'' (2007) was able to demonstrate that it was the mechanosensors that were responsible for flight stability as opposed to the other sensory organs, because when the flagella were removed and then reattached, all antennal nerves were severed excluding those at the base (Böhm's bristles and the Johnston organ).<ref name="Sane 2007" />