Biological Sciences: Halteres of Flies as Gyroscopic Organs of Equilibrium

IN insects belonging to the group Diptera the second pair of wings is modified into a pair of dumbbell shaped organs, called halteres or balancers, which consist of a thickened base bearing numerous sense organs, a shaft, and a swollen blood-filled end (Fig. 1, A). During flight the halteres are vibrated rapidly through an arc of about 90° in the vertical plane with a frequency which is almost certainly identical with that of the wing beat. In Calliphora, Lucilia or Phormia this is about 200 times per second.