House flies live in close association with humans and domestic animals. It is considered a endophillic eusynanthropic fly, meaning it readily enters dwellings, and requires human or human-related environments to complete its lifecycle. These requirements include food for the adults, developmental media for the immatures, and protection from inclement weather in order to overwinter, as this fly does not have a true diapause. 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.