How to make your own solitary bee house

By Lise Mahnke

The honey bee (Apis mellifera), which is suffering from a deadly disorder, is actually an exotic insect which was brought to this country from Europe to pollinate the food crops originating from Eurasia. One third of this country's honey bees disappeared last year, on top of the third of their population lost the year before — a frightening proposition for anyone who eats. But honey bees are not the only pollinators we have: native pollinator's such as moths and solitary bees are present and can be encouraged to expand their population by providing proper habitat, including nesting sites.

Solitary bees don't live in hives the way honey bees do and they don't make honey. They aren't aggressive like honey bees and don't sting unless you torture them. They are much more efficient at pollinating compared to their continental cousins. Two of the types of solitary bees we see in this region are Leaf-cutter Bees(Megachile spp.) and Mason Bees (Osmia spp.). These bees usually nest in hollow stems of plants such as roses and raspberries, rotten wood or other narrow diameter chambers. We found leaf-cutter bee sites in the narrow slots between old wood shake shingles. Leaf-cutter bees cut a small diameter circle — perhaps 3/4" across — out of leaves to roll up and line the nesting tube. The female lays an egg, deposits pollen, then seals the chamber with mud, then laying another egg repeats the process until the chamber is full. Leaf-cutter bees especially like redbuds, lilacs, and roses in my yard. Some people are bothered by the scallop effect they leave on the leaf, but Iwelcome them to my garden — smiling when I see evidence of another species able to utilize plants that I enjoy.

So I decided to build a bee boudoir. This is how I did it, an amalgam of instructions from several sites including an ag station in Utah and the general design from Robert Engelhardt's piece on Wikibooks.

My daughter and I built a solitary bee house from scrap lumber and a few basic tools in about an hour and a half. I started with three end cuts of 2" x 6" construction grade redwood — one that is 13" long and two at 10". The roof is made of two 1" x 8" x 4" long redwood pieces. You can see the tools, hardware, wood, finish nails, 5/16" drill bit, glue, and sanding bloc in picture below:


I started the 5/16" hole centers 3/4" apart on a drill press then finished their 5" depth with a cordless drill. Cut 60 degree angles on the tops, sand, then glue the pieces together. Glue and nail the roof with the overhang in front.

I coated mine with vegetable oil and attached a bracket on the back.

I was trying to decide where to hang the nesting block, so it was just left on the deck for a week or so. Sure enough, a bee has already begun to fill it. In the last photo you can see four holes — the top left hole has been plugged with a grainy substance that looks like soil. I'm going to hang the house on a south facing wall where I can pull a chair up and observe the critters coming and going.