Making backyard 'hives' for native bees
We would like to make some homes for native bees for our backyard with rounds of oak wood coming from a tree which we recently removed. We need specific details about construction. I would prefer to not be removing and storing and cleaning cores, as I believe the bees are probably hardwired to do that for themselves. I have seen several species of what I think are native bees working (particularly) my mint and oregano, and I would like to let them know they are at home here.Can you provide information or suggest a reliable site? I am finding much complicated and conflicting information on the internet.
We have over 500 species of bees in Oregon. The bulk of these species (>70%) live in nests in the ground, but a few nest above ground in things like dead hollow stems or abandoned beetle burrows in logs. You can simulate one of these abandoned beetle burrows by drilling holes into a log. Different bees (as well as beneficial wasps) will holes of different diameters. When OSU surveys the state we use hole sizes ranging from 1/8 inch to 3/8 inch. The holes should be relatively smooth, without a lot of burrs to catch on the bees, so use very sharp drill bits. In a perfect world the holes would be at least 6 inches long, but drill as deep as you can (in short holes bees tend to raise too many males).
I would also retire the logs over time. Disease tends to build up in the chambers. To retire a log, put it in a box with a single 3/8" hole on one side. When the bees emerge in the spring, they will fly towards the light (i.e., the hole in the box) and not return to nest in the block of wood. At the end of the year burn the log.