Most sweat bees are small to medium-sized, 0.12 to 0.40 in long. They are generally black or metallic colored, and some are brilliant green or brassy yellow. Sweat bees are particularly numerous in North America. Although their small size makes them relatively inconspicuous, hundreds may swarm over flowers in gardens or meadows. Sweat bees visit a variety of flowers,but is particularly attracted to alfalfa and pollinates it very efficiently. They sting only if handled.
Most species nest in the ground, but some nest in wood. Nests usually consist of a single main tunnel having one or more clumped cells arising from lateral branches. In some species, the bees constantly guard the nest entrances.
Sweat bee is the common name for any bees that are attracted to the salt in human sweat. Their attraction to sweat makes them a nuisance, as they will sting if squeezed or squashed against one's flesh. Their sting is almost painless. However, individuals with allergies to any kind of insect stings should seek immediate medical attention.