Mason bees, leafcutting bees, and other cavity nesters are incredibly easy to please. The hype you hear about their tubes needing to be a specific diameter, or a special length, or placed in a particular location is mostly nonsense. Left alone in the wild (as they were for millennia) the bees find all types of cavities that please them, from beetle borings to woodpecker holes to hollow reeds. In the wild no one measures the diameter, cuts them to length, or holds them parallel to the ground. We humans can be terribly self-important.
But just like everyone else I have neat rows of little tubes—paper straws in empty vegetable tins—and the bees certainly use them. A tin full of straws takes about three days to fill at the height of orchard bee season. These early bees are followed by other types of masons and leafcutting bees, all angling for a spot in a green bean can. Luckily for them, my dog eats a can of green beans each and every day, so when a can fills up I simply pull it off the bee shelf and add another.
But the bees in the straws are the tip of the iceberg. These are the gregarious masons that like to live (it seems) on the same block as everyone else. Other individuals nest to a different drummer.
A couple weeks ago I was checking my honey bees when I noticed mason bees flying in and out of an empty hive that was sitting between two very active colonies on the edge of the woods. You wouldn’t think mason bees would go there, with the air teaming with pheromones and threatening sounds. Curious, I opened the hive and found masons actively building away. What cavities were they using? Brood comb, of course. If you think straws in a can are tightly packed, you ought to take a good look at an empty brood comb. Claustrophobia big time.
Seeing these nests reminded me that I had a section box from the previous year that held some mud nests. I went to check on the section box, which I had put outside a month ago, and sure enough two of the bees, Osmia aglaia, had already emerged. These bees, sometimes called berry bees, are active later in the season and reach their peak after the orchard masons are done for the year.
Many species of bee in the family Megachilidae nest in empty tubes and tunnels, so it is not too late to put out your cans and paper straws. Get a dog with a green bean fetish and you can keep filling cans all summer long.
Honey Bee Suite