How Insects Fly
Diptera
The Diptera, one of the most recently evolved insect orders, are the Red
Barons of the insect world. The common housefly (photo) has converted its hind wings
into stumps which act as a gyroscopes to stabilize it. This is the reason
why flies are able to dart about as they do, changing direction suddenly, turning right angles, even
flying backwards.

How Insects Fly...2, March 1996