Houdini Flies

The Houdini Fly is a new invasive pest in the State of Washington.  Here are pest alerts from the Washington State Department of Agriculture: PestAlert-HoudiniFlyFeb2020.pdf, and Oregon State University: a-new-pest-of-mason-bees-the-houdini-fly/.  

Houdini flies are classified as kleptoparasites. Meaning they steal the food of another animal. In this case, it is the food of your baby bees.  They enter your mason bee nesting tunnels and lay their eggs near the mason bee eggs. The Houdini fly maggots emerge before the mason bee larvae and consume all the pollen and nectar that was left for the baby bees. Your baby bees will starve and your colony will die out.

In the past, I used paper straws, because they were inexpensive, and easy.  At first, they seemed to be working wonderfully!  They were filling up quickly and the little ends were capped with mud.  The straws accidently got wet, and I had to carefully open them to save the cocoons. I was shocked to discover that 80-90% of my straws were full of this curly orange stuff and hundreds of little white maggots!!  Some quick online searches revealed hat my colony was destroyed by Houdini flies.

Houdini Fly Maggot Infestation in Paper Straws

Curly Orange/Brown Frass (POOP)

The best way to avoid this, is to open the nesting materials, inspects, and harvest the cocoons.

The University of Idaho has instructions on mason bee care here: Raising-Native-Bees-Mason-and-Leafcutter.pdf

The Benton Soil and Water CONSERVATION DISTRICT has an excellent page on harvesting, inspecting, and cleaning your cocoons for the best possible survival rate: time-clean-mason-bee-cocoons/ .