Cluster Fly vs Wasp Twisted-Wing Parasite

Side-by-side species comparison

Attribute Cluster Fly Wasp Twisted-Wing Parasite
Scientific Name Pollenia rudis Xenos vesparum
Order Diptera Strepsiptera
Family Calliphoridae Xenidae
Size 8-10 mm 2-5 mm (males)
Habitat Gardens Woodlands
Diet Parasites Parasites
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.

Wasp Twisted-Wing Parasite

An endoparasite of paper wasps where females spend their entire life inside the wasp host. Parasitized wasps are castrated and abandon their colony duties.

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Did You Know?

Female Xenos never leave their wasp host — they live, mate, and give birth to thousands of larvae while permanently embedded in the wasps abdomen.