What is Halteres?
[[File:Tipulidae April 2008-2.jpg|thumb|right|300px|Behind the [[thorax]] of this [[crane fly]] are two knobs on stalks. They are the halteres.]] '''Halteres''' are small knobbed structures modified from the hind wings in [[Fly|flies]]. They [[Vibration|vibrate]] during flight, and help the insect fly better. The halteres evolved from [[wing]]s. Ancestral flying insects had two pairs of wings, like [[dragonfly|dragonflies]], [[hymenoptera]] and [[lepidoptera]] still do. Flies have only the front pair of wings. == Function == Halteres help [[Balance|balancing]] and improve flight. They help flies to perform their fast [[aerobatics]]. In addition to providing rapid [[feedback]] to the [[muscle]]s steering the wings, they also help [[wikt:stability|stabilise]] the head during flight. They are flapped rapidly and work as [[gyroscope]]s, telling the insect about its body position during flight.<ref name=klowden/> Every vibrating object tends to maintain its plane of vibration, a result of the [[Coriolis effect]]. If the body of the insect changes direction in flight or rotates about its axis, the vibrating halteres exert a force on the body. The insect detects this force with [[Sensory system|sensory organs]] at the base of the halteres. The two halteres vibrate in different planes, each forming an angle of about 45 degrees with the long axis of the insect. This increases the information got from the halteres. == Development == In Diptera, the formation of the haltere during [[metamorphosis]] is dependent on the [[Hox gene|homeotic gene]] ''Ultrabithorax'' (Ubx). If this gene is experimentally deactivated, the haltere will develop into a fully developed wing.<ref name=klowden>Klowden M.J. 2007. ''Physiological systems in insects''. Elsevier/Academic Press. 497–499</ref> This is an excellent illustration of an important mechanism of [[Evolutionary developmental biology|evolutionary development]]; a simple homeotic gene change can result in a radically different [[phenotype]]. == Convergent evolution == The [[St