; class Insecta, subclass Pterygota)
Order of insects in which the adults have a single pair of membranous wings, the hind wings having been modified into halteres. The mouth-parts are generally adapted for sucking, and modified into a proboscis, often adapted for piercing. Mandibles are absent in many families. Metamorphosis is complete. Larvae lack true legs and are eruciform, with up to 12 abdominal segments. Larval habits range from phytophagy to parasitism. The number of larval instars ranges from three (Cyclorrapha) to eight (Brachycera). The order is one of the largest within the class, having more than 85 000 described species. Most authors recognize three suborders: Nematocera (21 families), Brachycera (15 families), and Cyclorrapha (57 families).
Subjects: Zoology and Animal Sciences.