Thaumaleidae, the solitary midges or trickle midges, are a group of nematoceran flies related to the Ceratopogonidae, Chironomidae, and the Simuliidae. They are small, stocky, yellow to brown flies (3-4 mm). Very few species are known for this family (about 120 species in five genera). Larvae are found in films on rocks and the nonfeeding adults are usually found on foliage along the same streams in which the larvae are found. A few solitary midges are found in the Southern Hemisphere, but Thaumaleidae are generally an Holarctic family.