Sweat Bees

When I'm working outside in the summertime, I'm often annoyed by small bees that would rather land on me than the flowers I'm tending.

They're sweat bees, and range in color from black to metallic green, depending on the species. They feed on pollen and nectar, but they're also attracted to human perspiration, of all things. Ken Holscher is an extension entomologist at Iowa State University, and says that's how they got their common name.

"Everything I read says that they're attracted to the salt content, but why they need salt I'm not exactly sure," says Holscher. "People seem to be annoyed by them when they're out where they're working out a sweat in areas where they happen to be. And then they feel something crawling on their skin, and reflectively they just reach out there and smash it a little bit. If they do that, the females, if they feel threatened like that, they'll give you what I call a mild sting. But you feel something crawling and you know they're around, just kind of flick them off your skin and you'll be fine."

Holscher says sweat bees nest in the ground and are considered "communal" bees. If you see one, there will probably be more, but they don't live in colonies or hives. Females dig burrows deep in the ground and create small cells where they store pollen and nectar. In each cell, she lays an egg. The insects prefer dry soils and tend to avoid nesting in damp areas.

If you don't mind them checking you out to satisfy their salt craving, sweat bees can be beneficial to have around.

"Sweat bees are good pollinators of wildflowers, and so I don't think there's any reason why we need to get rid of them or try to control them if they happen to be in an area," says Holscher. "They're good pollinators of some things, but not collectively of all things."

Some of these docile creatures have a mean streak. There are parasitic species of sweat bees that invade the nests of other bees and lay their eggs in the food stored by the host bee. The hosts are usually other sweat bee species.