Why the population of house files does suddenly increases in summer?

The breeding season of house fly, Musca nebulo, is from March to October in most of India. In the course of the breeding season, a single female may lay eggs 4 to 6 times and each time each female lays 120 to 160 eggs. They lay their eggs in clusters on compost, waste heaps, manure and dung. The conditions required for laying eggs are moisture and favourable temperature. The eggs hatch in 8 to 24 hours depending on the temperature. The whitish larvae moult twice to become the familiar white maggots in 5 to 7 days.

The maggots transform into quiescent reddish brown pupa from which the adult flies emerge after 5 days if the temperature is optimum. Summer provides all the favourable conditions. So the flies mate and lay a number of eggs and suddenly increase their population within 15 day.