The period from 1917 to 1941 constituted an important stage in the formation and development of research schools in entomology in the city on the Neva. The deeply rooted research on zoological systematics centered around the Zoological Museum, which produced groups of specialists on insects, such as the dipterological school of A. A. Shtakel'berg. Another entomological school developed at St. Petersburg University, where in 1919 M. N. Rimsky-Korsakov established a special chair and unit on entomology. After 1930 the group continued its work under the direction of B. N. Shvanvich. By the end of the 1930s, conditions were ready for a new direction of investigation - the adaptation of insects on the basis of an ecologico-physiological approach -developed by A. S. Danilevskiy's school on photoperiodism. The majority of schools in applied research formed at specialized institutions of higher leaning - the Institute of Forestry, the Military Medical Academy, the Leningrad Agricultural Institute, and the АН-Union Institute of Plant Conservation. Corresponding schools associated with N. A. Kholodkovsky, M. N. Rimsky-Korsakov, E. N. Pavlovsky, and G. Ya. Bei-Bienko developed in the fields of forest, medical, and agricultural entomology. Not surprisingly, the largest schools evolved in areas associated with important state tasks such as the surveying of insect species and populations, and protection against pests and carriers of disease.