order of insects From Wikiquote, the free quote compendium
Flies are insects of the order Diptera (di = two, and ptera = wings). They possess a pair of wings on the mesothorax and a pair of halteres, derived from the hind wings, on the metathorax. The presence of a single pair of wings distinguishes true flies from other insects with "fly" in their name.
Seamless Wikipedia browsing. On steroids.