Leaf Cutter Bees -- Preferred Hole Size = 3/16"

There is an old wooden chicken coop near one of my fields which is highly favored as a nesting site for leaf-cutter bees. This summer I conducted an experiment to see which size holes they prefer.

A month or so ago I installed a board into the building, right next to the door, into which I had drilled holes of many different sizes. The only species that has nested in the board so far are leaf-cutters. The bees hatch about the time sunflowers bloom, so I installed the board before they hatched in the third week of July...

The bees occupied holes ranging in size from 1/4" to 5/32". The first hole occupied was 11/64". The most preferred hole size was 3/16" (5 mm) and anything between 5/32" and 7/32" had good occupancy rates.

Here's what the data and experiment looked like:

Preferred Hole Size: Leaf Cutter Bees in old building in Cache Valley


Experimental Design:

So what your saying is that size has more to do with it than how I need or use whatever it is they build their nest? Odd!, all this time I thought it was some kind of bee vendetta.

Thanks for doing that smart/hard work!

Perhaps I need to take my cordless drill and put and patch of different sized holes in all of the 4x4 vertical boards on my fence. Then different species will love different things. Maybe one patch of 3/16 plus one random size in each board.

I hear that as long as the holes are not to closely together that they will not effect the integrity of the fence.

Or.... I could just screw on small chunks of untreated 4x4 boards here and there. Actually that sounds even better since I could take them with me or give them away to friends/family who want bees too. Maybe for trade or profit.