Monography on the species composition and ecological characteristics of insects living on one of the largest in Central Europe bogs "Yelnia" (North-West of Belarus). In the course of many years of field research, the author collected and analyzed great stuff. A specific complex of insects was recorded. It comprises an approximately small number of species with a high abundance of some of them. Many of the insects are highly specialized to the ecological conditions of the bog (tyrphobionts and tyrphphiles). These species are good indicators of any change in the specific ecological conditions of peat bogs. The insect fauna of the peat bog Yelnia is unique for the temperate zone as it includes of relict boreal, boreomontane, arctoboreal and subarctic species. From a zoogeographical viewpoint, the fauna composition of Yelnya has groups with a Holarctic or Palaearctic range. The specific composition of the peat bog Yelnia in general is close to the species of Northern, Eastern and Central Europe.