''This article concerns insect anatomy. For halteres as used in ancient sports, see Halteres (ancient Greece)
Halteres (singular halter or haltere) are small knobbed structures found as a pair in some insects. They function as accelerometers to help the insect maintain stability in flight, analogous to an aircraft's attitude indicator.
The halteres evolved from wings. The ancestral insect species had two pairs of wings (like dragonflies and most other flying insect species have). In the Strepsiptera the forewings evolved into halteres, while in the Diptera (flies, mosquitoes and gnats) the hindwings changed into halteres.
Halteres operate as vibrating structure gyroscopes. They flap back and forth as the wings do, tending to vibrate in a particular plane. If the body of the insect changes direction in flight, a Coriolis force develops on the vibrating haltere, deflecting it from its stroke plane. The animal detects this deflection with sensory organs known as campaniform sensilla located at the base of the halteres. Halteres thus act as a balancing and guidance system, helping these insects to perform their fast aerobatics. In addition to providing rapid feedback to the muscles steering the wings, they also play an important role in stabilizing the head during flight.