Most gardeners are aware by now that honeybees are in trouble. This knowledge is driving a surge in amateur beekeeping. Other pollinators, including native bees, are in trouble too, from the same disastrous cocktail of causes — habitat loss, pesticides, disease and parasites. Keeping a hive of honeybees is quite a commitment, and for gardeners and small orchardists, encouraging native bees is a pretty good option. You can do it by growing native plants; leaving some areas, shall we say, unmaintained; and by providing nesting opportunities. One of the easiest native bees to accommodate is the orchard mason bee, which happens to be a champion pollinator.
Orchard mason bees have been commercially available for some time now, but I recently came upon a very local source. Last month I visited Jack Clark at his home in Springfield. He laid out the virtues of these shiny, blue-black bees, claiming that they operate on cool, cloudy days that discourage most other bees and have a preference for fruit tree blossoms. They don’t waste time and energy making wax or honey, he said, and they hardly ever sting.
Mason bees nest in pre-existing tubular holes in wood or in dry, hollow stems of plants. They are solitary — they don’t have a social structure or share and divide labor. In fact, they don’t interact at all with one another, except for sex. But they do like to live close to others of their species. This lifestyle makes it easy to provide them with man-made housing. Any structure you can devise that contains hollow cylinders of their preferred dimensions will attract mason bees if they are present.
Orchard mason bees are active for about three months each spring, beginning in early March. Males emerge first and do a little pollinating while they sip nectar and wait for females to emerge. Once mated, a female will find and mark as her own a suitable tubular hole or crevice for a nest. She then goes straight to work foraging pollen and nectar, which she packs in the back of the hole. She lays one egg on top of its food supply, then makes a mud wall to seal the cell before going to work on the next cell. The first few cells in each nest she fills receive fertilized eggs that will develop into females. Subsequent cells receive unfertilized eggs that become males.
The female bee continues to lay eggs in individual, provisioned cells until she has completed five to 10 finished cells. She then seals the entrance to the hole with an extra-thick mud wall and goes in search of a new nesting site. Given an adequate food supply and a source of damp soil, one female will fill several nests before she dies. The larvae hatch, grow, spin cocoons and, by the end of summer, develop into adult bees that remain secure inside the nest until next spring.
Jack Clark houses his orchard mason bees in pieces of untreated, 8-inch fir board, in which he drills 3/8 inch diameter holes, starting from the narrow edge. Into the holes he slides special paper tubes, 5/16 in diameter. Starting later this spring, Clark will sell dormant bees. Contact him at 741-7724. His price is $37.50 for three tubes, each containing eight to 12 bees. He’ll throw in a pre-drilled “starter block” to put the tubes in. Locate the block somewhere where it receives sun in early spring but is sheltered from rain. Bees will emerge around March 1 of next year and go right to work.
Meanwhile, you should acquire or build your own bee condominiums in preparation for next year’s population explosion. Drill holes in 6- to 8-inch boards, drilled from the short edge. (In the past, 4 x 4-inch blocks were recommended, but the deeper holes give the bees more protection from parasites and predation by birds.) If you drill all the way through the block, seal off the light at the back. Drill 5/16-inch holes for the bees to use as-is, or 3/8-inch holes if you plan to insert paper tubes. The tubes make it easier to re-use your blocks without extensive cleaning, and you can store filled tubes separately from your blocks. You can buy tubes at Down to Earth.