I was cleaning my mason bee cocoons (I know, it's the wrong time of year to do this) and I found some strange cocoons among the bees (see photo below). On the left are bee cocoons, on the right are the odd ones. They are dark brown, cylindrical, and have a tan tip on one end. The are made of a papery material, rather than silk. Any ideas what they are?
Thanks for any help!
The image does not appear in my browser, just the outline.
I am having the same problem as Larry G.
Yes, that worked.
Looks like they might be cocoons of beneficial wasps that parasitize spiders:
Hmm, thanks, Jafar, that's a good resource. Mine don't look quite like the Trypoxylon referenced there, but similar - maybe a slightly different species. It does allay my fears a little. I've sorted them out from the bee cocoons; maybe I'll go ahead and let them hatch.
I attended a Pierce County Washington Master Gardener talk yesterday about mason bees. The presenter said that Houdini flies are starting to become a problem in backyard mason bee colonies. The tiny fly sits on the bee block and goes into the tube after a bee leaves and deposits her eggs.
I recently read about the Houdini fly. Poor Mason Bees. Is it possible to stop the flies from entering the tubes, as unlikely as that sounds?