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 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. Strepsipteran haltere Strepsipterans are a unique group of insects with major sexual dimorphism. The females spend their entire lives in a grub-like state, parasitizing larger insects. The only time they ever come out of their host insect is to extend their fused heads and thoraces for males to notice. The males are also parasites, but they eventually will leave their 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. 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. For simplicity, the remainder of this article will refer only to dipteran halteres. Lepidopteran antennae Certain lepidopterans (moths and butterflies) exhibit small amplitude oscillation of their antennae at constant angles during flight. Antennal movements in lepidopterans were originally hypothesized to aid in wind or gravity perception. A study performed using the hawk moth, Manduca sexta, confirmed that these tiny, antennal oscillations were actually contributing to body rotation sensation. 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