none General morphology; Nutrition; Diet; Life cycle and development; Life cycle; Developmental stages; Development; Evolution; Variation; Parasites diseases and disorders; Parasites; Helminth parasites; Insect parasites; Hosts; Insect hosts; Host parasite relationships; Diseases and disorders; Diseases; Microbial diseases; Ecology; Habitat utilization; Abiotic factors; Physical factors; Land and freshwater zones; Palaearctic region Microsporidiidae (Microsporida); Life cycle stages; Morphology; Dipteran hosts; Tabanidae, larval host ecology; Prevalence; Reaction of host to parasite; Tabanidae (Diptera), pathogenicity & host ecology, review; USSR, prevalence & pathogenicity, ecological review Mermithidae; Steinernematidae (Nematoda ); Gordiidae (Nematomorpha ); Braconidae; Pteromalidae; Diapriidae; General morphology; Morphology; Dipteran hosts; Tabanidae, larval host ecology; Prevalence; Reaction of host to parasite; Tabanidae (Diptera), pathogenicity & host ecology, review; USSR, prevalence & pathogenicity, ecological review Phoridae; Tachinidae; Bombyliidae; General morphology; Morphology; Dipteran hosts, larval host ecology; Prevalence; Reaction of host to parasite; Tabanidae, pathogenicity & host ecology, review; USSR, prevalence & pathogenicity, ecological review Tabanidae; Diet; Prey; Composition, larval feeding ecology; Larva; Morphology, development & ecology, parasites & diseases; Growth, influencing factors; Morphological variation; Ecotypes; Larval, differentiation; Fungal parasites; Nematode parasites; Mermithidae & Steinernematidae; Nematomorphan parasites; Gordiidae; Dipteran parasites; Bombyliidae; Phoridae & Tachinidae; Hymenopteran parasites; Braconidae; Diapriidae & Pteromalidae; Protozoan parasites; Microsporidiidae; Reaction of host to parasite; Disease & parasite pathogenicity, host ecology review; Bacterial diseases; Fungal diseases; Viral diseases; Prevalence & pathogenicity, larval host ecology; Ecology, review; Habitat preference; Larval ecology relationship; Climate and weather; Temperature; Larval distribution & development relationship; USSR; Distribution, larval development & ecology