The female housefly lays about 50 to 100 eggs at one time in organic debris. The eggs will hatch into maggots in a mere 12 hours after being deposited. These maggots will feed on the organic debris and then each will build a cocoon where it will pupate and turn into an adult housefly.
It’s a good thing that houseflies can only survive for about two to three weeks at most, because during that time, a female can lay over 500 eggs. If even half of those eggs are females, and each of those females can produce 500 eggs, and so forth, it is no wonder flies are found in endless numbers!
Female blow flies live between 2 to 8 weeks, but they can lay thousands of eggs during their short life span. Eggs can hatch within 24 hours under ideal conditions. Their larvae develop inside rotting animal carcasses, causing it to take on a bloated appearance.
Female flesh flies’ eggs hatch in the female’s body. She then deposits up to hundreds of larvae inside a decaying host, such as a rotting animal carcass or on rotting meat. The larvae feed on the host for about 4 days. The adult flesh flies emerge in about two weeks, and repeat the same reproduction cycle.