Identify what is inside your nesting block during a MASON BEE HARVEST 

Good video. This is my first year to process the Mason bee tubes, though I have had them for several years with a great hatch last spring (2023). Being February, I am later than recommended. I just found the excellent video from Rent Mason Bees on how to clean and maintain the tubes. My initial hives, like yours, are made out of wood on a router. My grandkids gave me a house made of bamboo. Shorter than I like but the bees did not care. I split the bamboo open and will replace with longer bamboo harvested from bamboo patches in the area. Your video helped me ID the "free loaders". I only found 1 patch of pollen mites and one Houdini fly pupa with the yellow cottony looking frass. I watched your video again and realized I did have a few with the Chalk Brood. When I found them I wondered what those dead larva were. Now I know. I found a couple of other critters. I found several live larva, I suspect a beetle larva as they had 6 legs, so not a fly maggot (Diptera larva never have legs). I did not see prolegs so probably not a moth caterpillar. I will attempt to raise them to adulthood. I put the bee boxes in an glass fish tank and covered it with a screen for over the summer and away from predators (mice and larger insects). I found a lot of tiny wasps in the bottom. I noticed if there was a pin hole in the mud cap, the first chamber had been destroyed. No wasp larva either. Like an apple, if you find a "worm hole" in the apple the insect hatched. They were not flies as they had 4 wings. Your inset picture of the Houdini fly I suspect is actually a Mono wasp. The antennae are totally different. Wasp wings are often hooked together so the pair looks like one. I found a picture of them from your own site.

Thanks for the information. The presenter is just lovely.