InterL 21OC07 not available During the research periods (1966-2002) in Lithuania were found 163 fungus gnats species and 136 Orthocentrinae species. In the course of investigations there were 58 species of Mycetophilidae, 8 species, of Blitophilidae, one species of Ditomyiidae and one species of Keroplatidae reared from fruit bodies of macromycetes. Trophic relations between fungus gnats and more than 80 fungus species, belonging to 45 genera, were established. There were Orthocentrinae of 13 species reared from eight species of fungus gnats trophically related to fungi of nine genera (Agaricales s.l., Aphyllophorales). The widest diversity of fungus gnats and Orthocentrinae was established in the habitat of broad-leaved deciduous forests. Sciaroidea (Nematocera) : Host Orthocentrinae (Ichneumonidae) : Parasite Nutrition; Diet; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Ecology; Community structure; Habitat; Terrestrial habitat; Land zones; Palaearctic region; Eurasia; Europe Orthocentrinae; Dipteran hosts; Recorded; forest; Sciaroidea; Forest and woodland; Lithuania Sciaroidea; Food plants; Recorded; forest; Fungi; Hymenopteran parasites; Orthocentrinae; Species diversity; Habitat comparisons; Forest and woodland; Lithuania