Page "Halteres" Paragraph 4

Halteres flap up and down as the wings do and operate as vibrating structure gyroscopes.

Every vibrating object tends to maintain its plane of vibration if its support is rotated, a result of Newton's first law.

If the body of the insect changes direction in flight or rotates about its axis, the vibrating halteres thus exert a force on the body.

The insect detects this force with sensory organs known as campaniform sensilla located at the base of the halteres.

The planes of vibration of the two halteres are orthogonal to each other, each forming an angle of about 45 degrees with the axis of the insect ; this increases the amount of information gained from the halteres.