Adult house flies have sponging mouthparts, and therefore do not feed on blood. The flies feed on a variety of solid or semi-solid material, including manure, animal feed, sugars, broken eggs, and milk. Protein is required for egg production. Up to 120 eggs may be laid at one time with some flies surviving to lay two or more batches of eggs. Eggs hatch in less than 24 hours.
Immature development is highly dependent on temperature.
The larvae pass through three instars, then transform into pupae. The adult fly emerges from the pupa to begin the next generation. The seasonal activity of house flies varies with the regional climate. Peak activity usually occurs in midsummer. In southern Alberta, flies are active from May to October with peak activity in July and August.