Bumble bees are important pollinators around the world. Multiple recent studies have shown that certain bumble bee species have experience dramatic declines in recent decades. If you want to support the bumble bees in your local area, in addition to planting flowers, you might want to try building a bumble bee next box.
Build a bumble bee nest.
· Use wood that has not been pretreated. In total, the nest should be about 9 inches deep, 6 inches wide, and 6 inches tall. Within the nest, you will need to build two connecting chambers: a vestibule, about 3 inches long, and a nesting compartment, about 6 inches long. When bumble bees enter their nest, they defecate in the vestibule before entering the nesting compartment.
· Drill two to six ventilation holes in the top of one of the side walls, and cover them with fine mesh or netting so that ants cannot get in. It is best to glue the netting in place, as ants will find their way around staples.
· Drill a large diameter hole (1/2 to ¾ of an inch) near the base of the vestibule as an entryway, and also one near the base of the inner wall, so that the bees can get from the vestibule to their nesting compartment.
· Once your nest is built, lay corrugated cardboard on the bottom of the nesting compartment to absorb extra moisture. Put wool, cotton, dried grass clippings, or moss into the nesting compartment for the bees to use (Bumble bees naturally nest in mice nests, which come prepackaged with nesting materials).
· Put a short piece of PVC pipe into the nest entrance to minimize water getting into the vestibule.
· Place the nest near a tree, a fence, a row of shrubs. Pick a location that is warm (preferably south-facing) and dry, but shaded from direct sunlight.
· Put a ‘roof’ over the top of your nest box so that it is sheltered from rain, strong wind, and snow.
· Place a log or a large rock on top of the nest box so that it can’t be carried off or blown away.
· It may take a year for the nest to be ‘seasoned’, discovered, and deemed acceptable by spring foundresses.
· Another way to build a bumble bee nest is to get a medium-sized flower pot (either clay or plastic is fine) and bury it upside down in the ground. The drain hole on the bottom (which is at the top) serves as an entrance. Place a thick layer of gravel on the bottom for drainage, put a roof over the top so rain doesn’t enter the drain hole (a board, resting on a few rocks so that it is elevated just an inch off of the top of the flower pot will suffice), and add cotton, wool, or grass clippings for nesting material.