Darwinged Fungus Gnat
Introduction
The common name of gnat is applied to certain small flies, and that of
fungus which comes from their common occurrence on fungi which serve as a
major food source for their larvae; darkwinged describes the
smoke-colored wings commonly found within the Sciaridae. These flies
are nuisance pests in and around structures, but a few species are
agricultural pests. For the Sciaridae, about 137 species, and for the
Mycetophilidae, about 714 are found in the United States and Canada.
Recognition
Adults are about 1/23-7/16 inch long; slender to moderately robust,
longlegged, somewhat mosquito-like. Color usually black, brown, or
yellowish, sometimes brightly colored wings, usually smoke-colored or
sometimes patterned with darker areas. Head with eyes separated or
touching present. Antenna usually with 16 segments. Wings with front
margin thickened to near wing tip; basically and forking beyond middle
of wing and cubitus forking in basal quarter of wing; Mycetophilidae
with radial sector simple/unbranched or two-branched. Legs with coxae
elongated, tibiae with one or two special spurs, pupil absent or minute and
narrow to broad but much shorter than claws.
Mature larvae usually are slightly longer than respective adults; sciarid
larva with shiny black head and a 12-segmented essentially featureless
white translucent body, terminal abdominal segment with a
ventral/bottom lobe which acts as a proleg; mycetophillid larva usually
cylindrical and slender, with a well-developed head, and 11 or 12
segments, most segments often with entral creeping welts.
Habits
Adults typically are found on or near larval food materials. Larvae
fed primarily on fungi growing in the soil and moist decaying organic
matter. Sciarid larvae mostly feed on decaying plant material, animal
excrement, or fungus, but some feed in rotting wood or under bark of
fallen trees. Several sciarid species are economic pests in greenhouses
and commercial mushroom houses, and the larvae of the potato.
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