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Tricholauxania praeusta

Measuring some 4 mm only Tricholauxania praeusta is a small fly in the Lauxaniidae fly family. All flies in this family are small, measuring between 2 and 7 mm. The family is comprised of some 1,900 species, of which 200 species live in Europe. The flies are yellow, brown or black or a combination of these colours. The larvae are important, for they help recycling decaying plant material. Most species live in leaf litter, but some in dead tree stumps or other decaying wood, or in old bird's nests.

Tricholauxania praeusta is yellow, often a pale kind of yellow, but it may be an orange kind of yellow as well. Adults are often seen on top of leaves sunbathing or drinking nectar from flowers such as hogweed. The larvae live in leaf litter, eating rotting leaves. They often mine these leaves, which means they live inside the leaf, between the upper side and the underside, leaving these two intact. The larvae are real maggots: they have no obvious head and no legs. Under the right conditions they grow very quickly: the three instars they go through may be finished in just one week. From egg to adult fly may take three weeks only. Adults are seen from May to October. Tricholauxania praeusta is a common and widespread species all over Britain and Ireland.