This book deals with the ichneumonid subfamily Cryptinae, 672 species of which belonging to 104 genera have been recorded in the territory of the former USSR. Eleven species are described as new. The book is arranged in 9 chapters as follows: natural history of the studied territories and methods of investigation; faunal composition of the Cryptinae of the USSR and a brief description of their characteristics; trophic relations of the Cryptinae of the USSR; structural differences in distribution of complexes and individual ichneumonids and their interactions with hosts in various ecosystems; population dynamics of host-parasitoid complexes and their mathematical modelling; some regularities in the population dynamics and spatial distribution of host-parasiitoid complexes; functional dynamics of host-parasitoid complexes in various ecosystems; dynamics of phenology in host-parasitoid complexes; changes in fluctuation in phenological cycles of host-parasitoid complexes in natural ecosystems; and principles of conservation of host-parasitoid complexes. none