The microhabitat preferences of Stiletto-fly larvae were investigated in two mountain primeval mixed forests. Larvae were sampled direct from the soil and reared in the laboratory. Variables describing the characteristics of particular microhabitats were noted and analysed. Four species of the family Therevidae were recorded: Thereva handlirschi (Kröber, 1912), Thereva microcepahala (Loew, 1847), Thereva valida (Loew, 1847) and Pandivirilia eximia (Meigen, 1820). T. microcephala was the dominant species. The tendency of therevid larvae to inhabit specific microhabitats within the heterogeneous environment of the primeval forest is described.