Cluster Fly

Natural Habitat

Typically found outdoors in fields and gardens during warm months; they enter houses and buildings to hibernate in wall voids or attics during winter.

Diet & Feeding

Larvae are parasitic on earthworms; adults feed on plant nectar, fruit juices, and other organic liquids.

Behavior Patterns

They are known for 'clustering' in large numbers in attics or window frames as cold weather approaches. They have a sluggish, clumsy flight and often drop to the floor when disturbed.

Risks & Benefits

They do not bite humans or carry diseases associated with filth like house flies, making them primarily a nuisance. In the ecosystem, they help regulate earthworm populations.

Identified on: 3/21/2026