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USDA Alert: Houdini Fly

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Houdini fly larvae inside a Mason bee nest.

The USDA warns of an invasive parasitic fly species spreading across North America. Known in Europe as the Houdini fly, this pest threatens the mason bee industry. The Houdini fly, Cacoxenus indagator is a kleptoparasitic pest that is well-known in Europe and found in the nests of red mason bees (Osmia bicornis). A member of the fruit fly family, this small fly is named after its ability to erupt out of the mud walls of mason bee nests.

Kleptoparasites are animals that steal another animal’s food, a good example is the cuckoo bird. The Houdini fly waits for the mother mason bee to gather sufficient pollen and nectar and crawls into the nest to lay eggs before the nesting chamber is sealed with mud.

Learn how to reduce this pest’s impact and protect your mason bee population.


Washington State University