Ground-Nesting Bees
Meet the Miner and Sweat Bees
By Sara Wright
Last night around dusk, Coalie, my dog, discovered a ‘volcano’ in one of her favorite spots. Keeping a sharp eye on her, I immediately went over to investigate, thinking it might be a toad who, if annoyed, could exude toxins. But no, Coalie was nosing around a new sweat bee volcano. The hole in its center was the doorway to the bee’s underground tunnel. Someone must have been home because Coalie suddenly jumped away, shook her head, and stuck her nose in the grass nearby. A warning or a sting? I can’t be sure, but my guess—it was just a warning because these ground bees are not aggressive and rarely, if ever, bite.
Both miner and sweat bees, two types of ground-nesting bees found around the world, are abundant residents at my cabin. Both are smaller than honeybees, and the nests of both have slightly raised soil mounds with a small central hole—volcanoes. Nests for both can be clustered together in close quarters. It is easy to distinguish the smaller miner bee ‘volcanoes’ from the larger mounds produced by sweat bees. Each prefers slightly different habitat.
The main difference between the two bees lies in their social structure and timing. Here is a little more about each of these bees:
Miner Bees. Miner bees are often mistaken for bumblebees because they are black and yellow. A number of different species can be found throughout Maine. Miner bees have been known to nest in the same location for many years. (Based on personal experience, I would say the same for sweat bees.) Around here, I see them during the spring. Miner bees are strictly solitary, with a single annual generation active for a brief spring window, after which they mostly disappear.
Sweat Bees. Sweat bees come in many colors! Some species are plain black or dark brown, but others feature bright, shiny metallic colors like green, blue, or purple, and some display red or yellow bands. The green ones are easy to identify. Pinpointing the others can be confusing. The name sweat bee developed out of the propensity for these bees to land on a perspiring person’s arm because of an attraction to salt. Sweat bees are harmless, only stinging if physically threatened. I find it is easy to ‘befriend’ one by talking to the bee in a low voice while walking around. Sweat bees range from being solitary to becoming semi-social, often producing multiple generations per year with overlapping adult-worker stages, so we see them throughout the summer months. Some species even change their social behavior depending on the time of year or the presence/absence of good foraging foods.
Both of these bees are such crucial pollinators of spring flowers, trees, summer flowers, and crops that it is important to keep them around. I deliberately create inviting habitat by leaving bare spots and lots of leaf litter around my house. Decaying logs pepper the ground under the ‘bee tree,’ a late-blooming hydrangea that sweat bees love.
All you have to do to invite them into your yard is to tolerate bare spots and allow those little mounds of raised soil.
Comments