How fast does a fly lay eggs?

Houseflies lay eggs in batches of about 100 every few days. Depending on the species, a female fly can lay up to 1,000 eggs in her lifetime. The eggs are white and about 1 mm long. They are usually laid on moist, organic matter, such as garbage, manure, or dead animals. The eggs hatch into larvae, or maggots, in about 24 to 36 hours.