The Nematocera (nemato+cera meaning "thread-horns") are a suborder of elongated flies with thin, segmented antennae and mostly aquatic larvae. This group is paraphyletic, containing all flies except for those of the suborder Brachycera (the name meaning "short-horns"), which includes species such as the housefly or the common fruit fly. Thus, the equivalent clade to Nematocera would be the whole of Diptera, with Brachycera as a "subclade". Families in Nematocera include mosquitoes, crane flies, gnats, black flies, and multiple families commonly known as midges.
The nematoceran imago typically have elongated bodies and legs, and many species have relatively long abdomens. They also have fairly long, fine, finely-jointed antennae; in many species, such as most mosquitoes, the female antennae are more or less threadlike, but the males have spectacularly feather-like or plumose antennae.