Four years ago I made my first orchard bee hive from a box of soda straws I bought at Walmart. I cut one end off the carton and left the straws in the box, and hung it in a sheltered corner of the front porch in early spring. That spring seven straws were filled, packed with pollen and orchard bee eggs and then capped off with mud. I found out that summer, by reading more about this, that soda straws don’t work very well. They trap moisture so fungi often kill the larvae before they mature into bees. A regular soda straw is also too small to favor development of a female orchard bee. Most of the bees that do survive the plastic tunnel will be male. So it was not a great start but I was encouraged that I at least have a few orchard bees in the area.
The next year I tried a bee log made from a section of maple branch I got by pruning trees in my yard. I hewed the end to a flat point, bored a hole through with an auger and bit brace, and hung it from the same hook where I had the box of plastic straws the year before. That spring the log was way more popular than the soda straws had been and about a third of the 5/16″ diameter tunnels I bored in it, 4 inches deep, had occupants by the beginning of summer. I lost a few of those in early fall when birds raided the log but caught it in time and got the bees through the winter by wrapping the log in chicken wire and plastic mesh. Before the third spring arrived I upgraded to a shield of hardware cloth in a half inch grid. I’d recommend setting this out several inches away from the log and leaving both top and bottom open. The bees try flying through the openings and go tumbling but eventually figure it out and learn to enter from the top or bottom of the log shield.
The third year, I had quite a swarm. Not just orchard bees, but mason bees worked the log, and in summer when the bee season had passed some of the remaining apartments were taken by small wasps. Well, I suppose orchard bees are a type of mason bee, but this other type was larger than a honey bee and smaller than a bumble bee and wasn’t quite such a neat mason as the little orchard bees. I also do not know what sort of wasp builds nests stuffed with long strands of straw but it was that kind of wasp and I’m sure they are good for something. That was last year, and I had so many bees working the first log that I built two more larger bee logs and strapped them to the porch post near the first bee log. The bees entirely filled the first log, the second log and part of the third log before the bee season ended.
That’s one drawback to raising orchard bees and “other” mason bees, they are only around and active in pollination during the spring, but they would be helpful in pollinating orchard trees and brambles and strawberries. They are the simplest pollinators to encourage because all you need to do is give them housing and protection from birds. I hang the bee logs under the porch awning, and facing away from the north wind and rain. When I run out of room there, I will experiment with hanging some from trees in the yard, facing south and capped with enough roofing to deflect some of the rain.
The little orchard bees are easily spooked and won’t go to their nesting log if you stand around too close. The mason bees also don’t like visitors, but although I had a healthy swarm swirling around these logs last spring and went out to observe them often, I could walk right past the logs without being stung. Both types of bees are solitary, so possibly they wouldn’t attack en masse. Occasionally one of the orchard bees would get feisty and threaten me with buzzing feints but never did anything more.
I wasn’t sure that bees would use the same tunnels year to year but they do. A few of the capped doorways showed pinhole pricks, so there’s some sort of wasp that also takes advantage of the sealed tube of goodies. The larval wasp probably eats the bee egg, too, but even a wasp needs food and shelter. Again, it’s probably good for something. When the bee or wasp digs it’s way out of the chamber, others clean it out and use it again. I don’t know the wasp that preys on tomato hornworms, but I’ve not needed to buy any of those. Every summer I find several unhappy hornworms with the pupal sacks of parasitic wasps sticking up off their backs in neat rows. Don’t bother a hornworm of that sort, it’s near death and won’t be eating much, if anything. Leave it and let the wasps finish their cycle. Then you’ll have more wasps to hunt down your tomato hornworms.
Wasps are not the only predators that target bee logs. Birds are the worst, especially woodpeckers of any sort. One thing not included in the commercial orchard bee nests is a bird guard, and that’s essential. After the nest is filled for the year, it has to survive until next spring. Woodpeckers and even other birds love these bee logs. Wire mesh was enough to keep the bees safe, until this winter. Somebody among my birdie friends discovered they could fit under the wire and attacked more than half of the bee tunnels in my logs, so I stuffed the openings full of plastic Walmart bags to save the rest. But! all is not lost. I suspected that the bees are prepared for these attacks and I was correct. According to experts at Washington State University, orchard bees create a string of cells in their tunnels, each with its own food supply and a single egg. The outer cells are vulnerable to birds but the inner cells can survive an attack. WSU did not say that last part, this is just what I’m thinking. If I were a bee this is what I would do. I will not abandon hope even for the damaged tunnels. Plus, the downy woodpeckers probably got a tasty treat.
WSU says tunnels from 1/4 to 3/8 inches in diameter work best for orchard bees. I’ve been drilling 5/16 inch diameter holes in the nests I set up. The size of the bee depends somewhat on the size of the tunnel. Since smaller holes favor male bees, and larger holes favor females, maybe I will change my plans this spring and include a range of sizes.