Family Thaumaleidae - Trickle Midges

Seepage midges, madicolous midges

Thaumaleidae Bezzi 1913

26 spp. in 2 genera in our area(1), ~200 spp. in 10 genera total(2)

2-4.5 mm(1)

Adults are recognised by the few (seven) veins reaching the margin, the costa running around the entire margin, by the absence of ocelli and particularly by the short antennae which are no longer than the head(3)

predominantly temperate areas of both hemispheres(3); in our area, n. US & Canada(1)

larvae predominantly in vertical, thin water films alongside waterfalls and torrents; undersides of bridges over smaller running waters are amongst the commoner adult aggregation sites(3)

larvae graze on diatoms(3)

"Larvae are found on wet rocks, most frequently on the vertical surfaces, and always where the surface is covered with a film of water thin enough not to submerge them. The rocks are located in cold streams, usually in the shade. When larvae are disturbed, they glide rapidly over the film of water on the rock surface; they feed mostly on diatoms found on the rocks (Leathers 1922). Pupae are found in wet moss or leaves, or buried in mud. Adults fly only a short distance from the larval habitat."(4)