Blue orchard bee-Houdini fly

Cacoxenus indagator

Pest description Houdini flies generally resemble fruit flies as they have dull brown bodies with large red eyes. They are kleptoparasites that lay their eggs in sealed brood cells. The fly larvae then hatch and come the pollen ball thus starving the bee larva. Infestations can appear as similar to that of chalcid wasps with white clusters of larvae in the nest cell. While the larvae look the same, Houdini flies adults are more lethargic and sluggish compared to that of the wasp adults.

Management Harvesting cocoons and squishing the sticky maggot larvae is the most efficient way of preventing and managing Houdini fly infestations. If nesting materials are not able to open, place the nesting materials in a fine mesh bag and tightly cinch it. Then, as the flies and bees emerge, release the adult bees daily and kill any adult Houdini flies found in the bag. Swatting adults or collecting them with an aspirator can also be used for some control near propagation sites.

For more information:

Natter, J. 2021. A new Pest of Mason Bees: The "Houdini" Fly. OSU Extension Service Metro-area Master Gardener Newsletter. Corvallis, OR (