Environmental factors influencing the number of preimaginal phases of development midges

In the South of the Tyumen region main places of hatching midges are of the Iset river, Pyshma and small rivers and streams. Depending on the season the number of midges may undergo major changes due to hydrological regimes of the rivers. High and prolonged spring flooding are favorable for the development of midges. The maximum density of larvae and pupae - 390 individuals per 1 dm 2 of the substrate was recorded in 2007, when the rivers were high and prolonged spring flooding. Minimum density of larval settlement phases in the development of midges was observed in 2006 and 2014, when the spring rise in water level in the rivers was low.