How do house flies overwinter?

House flies primarily overwinter as larvae or pupae rather than as adults or eggs. This choice is correct because the immature stages of house flies, particularly the pupae, can survive in a dormant state during colder months. In this state, they are protected from harsh environmental conditions, allowing them to endure until temperatures rise and conditions become suitable for emergence as adult flies.

In contrast, while house flies can lay eggs that hatch into larvae, these eggs do not survive freezing temperatures, making this method of overwintering less viable. Adult house flies are also more susceptible to mortality in cold climates as they lack the protective adaptations seen in their pupal stage. Lastly, stating that house flies only overwinter in warm climates misrepresents their ability to adapt to varying environmental conditions; those in cooler regions utilize the pupal stage to survive winter effectively.