I set up my mason bee nest in my garden about a month ago for the first time. The bees were filling the paper straws slowly till recently something started emptying the straws that had been filled once. I heard about parasitic wasps that attack their nests, but do they empty the nest completely in such a short time? I'm a complete beginner in this field and would appreciate advise. Thank you.
Parasitic wasps lay eggs in the nest (or possibly in the bee larvae) but do not disturb the nest. They usually leave a tiny hole in the side of the straw. It is far more likely that woodpeckers or Western Flickers have been poking into the open ends of the straws. They may reach one or two of the bee larvae but normally can't reach far enough into the straw to grab all of the larvae. The first cell in the straw is normally left empty anyway to deter such predators. Are you sure that the straws are empty? The other possibility is that something besides mason bees was filling the straws, because, if you actually set the nest out a month ago, there would be no mason bees around to use it. They usually finish laying eggs and die before June around here. By the time apple trees have finished blooming, all of the mason bees are also finished because that is the end of their food supply.
There are two books on Orchard Mason Bees written by Brian L. Griffin from Bellingham. The green one is the first and the orange his second. Both simply titled "The Orchard Mason Bee". Great resources. Vitog is correct. OMBees are only active in the early spring. He also wrote one called "Humble Bee Bumble Bee". Try contacting him if you can.
Thank you for the advise. I pulled some of the straws that I was sure had been filled earlier. The straws were empty about one to two inches from the front sides and deeper part were still filled. I am still hoping it's Mason bees who are filling the holes.... I guess I will find out next year. Barbara, I will definitely look for the books! Thank you very much again.
Four years ago I started my bees with the straws but found that some small parasite was drilling through the paper and getting to the larva so I would lose almost all my bees and had to start fresh each spring. Two years ago I switched to the plastic pre-drilled combs and now almost every one of my larva hatch out in the spring. I now have several large hives and harvest over a hundred larva each fall. You might want to invest in the plastic to prevent this problem. They are also easy to clean and disinfect, and therefor they are re-usable
