The larva of a housefly is called a maggot.
Life cycle of housefly
A housefly’s life cycle starts with the egg. A single batch of 150 eggs can be laid by a female housefly. She’ll lay five or six batches of eggs over the course of a few days. For egg laying, female houseflies prefer moist, dark surfaces like manure, compost, and other decomposing organic material. Some houseflies lay eggs that look like rice grains.
Within a day, house fly eggs hatch into larvae, also known as maggots. Maggots are legless white insects that feed from the egg-laying site for 3 to 5 days. During this time, maggots will hatch several times. They then choose a dark place to pupate.