The house fly passes through four stages in its life cycle: egg, larva, pupa and adult. The female of the species can be seen depositing their eggs on suitable breeding materials. Often, the females can be seen in clusters of up to 50 individuals. The female housefly lays individual eggs that pile up in masses of 75 to 150 eggs; in her lifetime, a single female house fly may lay up to 900 eggs. The female fly begins laying her eggs anywhere from 4 to 12 days from emerging from her pupae. She may lay 5 or 6 batches at intervals of several days between each.
Your inspection should begin outside the home or building; although house flies are known to breed in indoor dirty trash cans, they are usually found feeding and breeding in fresh manure, rotting fruits and vegetables, damp garbage and damp, decaying organic materials that are located outside of the structure. After locating all possible breeding sites, look for areas where house flies enter a structure. Cracks around windows, doors and vents are the usual culprits.