Cluster Fly vs Semaphore Fly

Side-by-side species comparison

Attribute Cluster Fly Semaphore Fly
Scientific Name Pollenia rudis Poecilobothrus nobilitatus
Order Diptera Diptera
Family Calliphoridae Dolichopodidae
Size 8-10 mm 5-7 mm
Habitat Gardens Gardens
Diet Parasites Omnivores
Regions Europe, North America Europe
Conservation Least Concern Least Concern

Cluster Fly

A medium-sized, dark gray fly with golden-brown hairs on the thorax. In autumn, it gathers in large clusters inside buildings to hibernate, sometimes in the thousands.

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Did You Know?

The larvae of this fly are earthworm parasites, burrowing into the worm through its skin and consuming it alive from the inside over several weeks.

Semaphore Fly

A tiny metallic green fly where males have conspicuous white-tipped wings used in semaphore-like courtship displays. It is extremely common around garden ponds and puddles.

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Did You Know?

Males stand on mud and wave their white-tipped wings like semaphore flags to attract females watching nearby.