Agapostemon virescens

Females have a metallic green thorax and a black-and-white striped abdomen.

Males are also bright green at the front, but their abdomen is striped yellow and black.

It lives mostly in the Midwestern and Northeastern United States, with sightings from coast to coast.

Nests are communal: a single entrance hole at the soil surface is used by several females.

There are no queens or workers: all females lay eggs and at least occasionally forage for pollen.

Mated females emerge from hibernation in mid-May and build nests underground.

When temperatures drop, mated females hibernate in the nests they were born in until spring, while the males die.

How many generations it has each year is not settled: a New York study treated it as having one generation, while other sources report a second generation emerging in late July to early August.

Up to two dozen females may share one nest entrance, but each female digs her own burrow inside.

Females visit a wide variety of plants and are especially fond of the daisy family, such as purple coneflower and asters.

Females take turns guarding the nest entrance, and having a guard lowers the chance of a visit from an unwanted intruder.

In a New York study, continuous guarding protected communal nests from the cuckoo bee Nomada articulata, which successfully attacked nests occupied by lone females.

In the same study, 58 percent of adult females switched nests during their adult lives.

The City of Toronto chose this bee as its official bee, partly because it is common, easy to identify, and tolerant of newcomers at its nests.