How to build a bee block
Of all the bees native to North America, about 30% use some kind of tunnel in which to lay their eggs. The diameter of the tunnels, as well as their preferred length, varies with the different species of bee. So, to attract a wide variety of native bees, it is best to use a wide variety of tunnel sizes.
The most popular bee tunnels range from about 3/32” to 3/8” wide. The narrower ones are usually shorter (about 3-5 inches) and the wider ones are longer (up to 6 inches). These numbers are not exact, so approximations work fine. The tunnels are easily made with a long drill bit in blocks of dimensional lumber or in the ends of bucked logs. Three important points:
- Use untreated wood
- The tunnels should be as smooth as possible
- The holes should not go completely through the wood (one end remains closed)
If at all possible, line the holes with paper straws or rolled wax paper. A paper liner does two important things:
- It keeps the inside of the nest smooth and snag-free
- It can be replaced every year, thereby reducing the accumulation of diseases and parasites.
Hang your bee boxes at least three to four feet off the ground so they don’t disappear among the weeds and to keep them away from splashing water and small animals. Early morning sun is okay, but the boxes should be protected from direct afternoon rays. Additionally:
- Add a small overhanging roof to keep out the rain
- Mount the boxes on a steady structure rather than one that sways in the wind
- A loose covering of wire mesh (like chicken wire) can help deter hungry birds in winter