Houdini fly

The Houdini fly, a small gray insect with red eyes, was accidentally introduced from Europe and has been spreading in Washington and Oregon.

Houdini Fly Hunt launched in WA, OR. Here's what to do if you spot one Kristina Moy 2025

The Houdini fly is a non-native kleptoparasite. What that means is that it does not attack mason bees directly, but lays its eggs on the pollen meant for the mason bee young inside of the nesting blocks. When the Houdini maggots hatch, they consume the food before the mason bee larvae, which causes them to starve. When the flies are fully formed, they escape from the sealed chambers, earning them the name “Houdini” fly.

Mason Bee Predator Alert – Invasive Houdini Fly Thyra McKelvie 2025