Diagnosis. Adults are rare, small to medium-sized (3.0-5.0 mm), dark brown to orange midges resembling Simuliidae. Head without ocelli; antennae short; mouth parts with 5-segmented palpi. Thorax with small spiracles; mesonotum often with a U-shaped colour pattern. Wing brownish translucent; Sc short; R1 elongate. Legs short; tibiae without spurs; claws simple; pulvilli absent; empodium small. Abdomen cylindrical greyish brown. Male genitalia not rotated, tergite 9 large; the shape of styles and parameres is specific. The lateral and ventral view of female terminalia is also specific.
Biology. Larvae and pupae are found in aquatic environments. Larvae live on the thin water layers in hygropetric zones of springs or banks of unpolluted streams, that are kept wet by spraying water. They hold on to the substratum with thoracic and abdominal pseudopodia. Larvae of different sizes are mostly found in spring and early summer on stones, moss-carpets, wet leaves and dripping rocks where they feed on the biofilm. Number of larval instars is high (>10) and does not seem to be fixed. Pupation often occurs in deeper layers of organic material near the larval habitats. Adults are bad flyers. Eggs, up to 0.3 mm long and with 8 deep parallel grooves, are glued to stone surfaces by the females.
General references. Stone & Peterson (1981 [general, key to genera]), Vaillant (1977 [general, key to species], 1981b [general, key to females]), Wagner (1997c [general, key to genera]).
References to the local fauna. De Meijere (1950a), Mol (1984).
How to quote this page: Wagner, R., & P.L.Th. Beuk, 2001. Family Thaumaleidae. In: Beuk, P.L.Th. (Ed.): Checklist of the Diptera of the Netherlands, https://diptera-info.nl/news.php?fam=Thaumaleidae (date accessed: 21/12/2024).
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