The fly family Dixidae, commonly known as meniscus midges for their characteristic larval behavior, is closely related to mosquitoes although they do not feed on blood. In fact, they do not feed at all as adults (Figure 1) and consequently are very short-lived. Dixid larvae (Figure 2) are important ecologically as filter-gatherers of organic matter and prey items for predatory insects and fish. Dixid larvae are frequently encountered during benthic macroinvertebrate surveys conducted by conservation agencies, such as the USFWS, EPA, and NPS. Adults are nondescript midges that are rarely encountered unless specifically sought
out by collectors. Late in the afternoon, near dusk, adult males of some species form small aerial swarms (leks) for mating purposes. Females lay small masses of eggs along the borders of suitable aquatic habitat. The Nearctic fauna is comprised of 45 currently recognized species belonging to three genera: Meringodixa, Dixa, and Dixella (Cook & Peters 1966; Peters & Barbosa 1970; Peters 1981, 1987). Larvae of Meringodixa and Dixella occur in calm waters, while those of Dixa are found in flowing reaches of streams of varying size. Larvae are often associated with streamside vegetation upon which they rest.