Backyard Bugs-Sweat Bees

VIRESCENT GREEN METALLIC BEES

Scientific name:Agapostemon virescens

This bee belongs to the larger family of HALICTIDAE, often known as sweat bees.

Physical description:

Typically these bees are 3/8-1/2" in size, and both males and females have a brilliant metallic green thorax. The abdomen is black with rings of yellow or white hair. Males have yellow legs. There are a number of bees that have metallic green bodies which can easily be confused with Agapostemon virescens. We were able to examine a male and female specimen from our colony using a microsope and were able to key them out to determine that Agapostemon virescens is what we have in our yard.

Range and habitat:

These bees are found from Quebec, south to Florida and west to Texas. Virescent green metallic bees do not live in hives, but instead live in small colonies underground. A mated female will dig a burrow, usually in sandy soil, with several different chambers. The female will then proceed to lay an egg in each chamber, place a pollen ball in the chamber to provide nourishment for emerging larvae, and then will seal the chamber. Entrances to the colonies look like ant hills with larger holes; as the colony increases in size, more entrances will be created. When I first noticed the colony in our yard three years ago, there was only one entrance. Last year there were three, and we are interested to see if the colony expands again this year.

Social structure:

Colonies are founded by a mated female that "overwinters." Usually females develop and emerge first from their brood cells, followed by the males. After the new broods mature, males and females mate, and females will dig more brood cells and expand the colony. Adults can be seen from April through late Fall, and we witnessed several as late as November 2001. These bees are not aggressive and you can get quite close to the colony without disturbing them. Interestingly enough these bees will "guard" each entrance, by posting an individual to keep watch and chase off unwanted visitors like parasitic wasps. Every evening the bees also "plug up" the entrance holes to protect themselves overnight, and usually reopen the entrances between 7:00-8:00 AM.