Halteres of a Crane fly. Macrophotograph of the head and thorax of a Crane fly (family: Tipulidae) showing the halteres. At top is the head with black compound eyes and mouthparts visible; a pair of wings and behind them long legs; short halteres posterior to the wings. Halteres are modified hindwings, formed into two drumstick-shaped structures which serve as balancing organs. The halteres vibrate when the insect is flying, and are thought to perform as gyroscopic sensors maintaining stability in flight.