The paper gives a historical account of investigations of mosquitoes, black flies and horseflies carried out by the staff of the Laboratory of Parasitology, Zoological Institute RAS, supervised by a corresponding member of the Russian Academy of Sciences, Prof Yu. S. Balashov, during 1979-1994. The research team of the laboratory explored the local fauna, relative abundance, seasonal dynamics, diurnal activity, longevity of a mass flight activity, annual fluctuations of the number, and age content of populations of various mosquito, black fly and horsefly species in the territory of Leningrad, Novgorod and Pskov Provinces. Attack peculiarities of various horse fly species were studied with the use of individual labeling.