Breeding sites include rotting organic matter, such as spoiled grain, dead birds or other animals in an attic or chimney, or a decaying bee nest in a wall. Indoor worm compost bins have been known to harbor soldier flies.

Where do house flies nest?

House Flies

Homeowners typically find house fly eggs in moist, decaying organic material like trash, grass clippings, or feces. Elongated and pale in color, they appear in clusters and hatch quickly after being laid by the female fly.

Why are there so many flies in my house all of a sudden?

The most common reason for flies swarming all over your house is an infestation inside or nearby your home. If you suddenly see a swarm of flies that means dozens of eggs have already hatched and developed into flies. The source is likely inside your house, garage, attic or garden.