Two years ago I had never heard of the Houdini Fly. However at that time they were starting to turn up in the Duncan area. This year I encountered them in several of my mason bee nest boxes I have placed on surrounding farms in the Metchosin area so they are a recent invading parasite for mason bee larvae production.
These are probably the most destructive parasites of mason bee colonies as they will eat through all the cocoons in a tube if allowed to remain through the fall and winter. The best solution is to clean out the mason bee incubating tubes as soon as possible, even as early as late August. It is important to leave those tubes that have not been sealed by then for a few more weeks in the bee house as later nesting leaf-cutter bees and other pollinating wasps and bees may still be working.
Not cleaning out your colonies early may lead to total cocoon production failure.
See this link for other parasites of mason bees:
https://gfletcher.ca/category/mason-bees-and-phragmites_reed-grass-tubes/mason-bee-parasites/
