Osmia sp.

Taxonomy

Bees in the genus Osmia, in the family Megachilidae, are known as the mason bees because many of them build their nests from mud. Some members even build free-standing nests. They overwinter as adults and are the first bees active as soon as the snow is mostly melted. If you see this taxa in your results, the specimen was too damaged to identify to species.

Description

Many Osmia sp. have a metallic blue-green shine to their exoskeletons. You may need to get them in the right light to see this color, otherwise they may look mostly dark.

Nest Structure

In Minnesota, Osmia lignaria is the only species that builds a mud nest. Other Minnesota Osmia sp. use chewed leaves as a building material.

Hole Sizes

No information at this time.

Voltinism

Univoltine, meaning they complete one generation per year in Minnesota. Both males and females overwinter as adults inside their cocoons.

Activity Period

Very early spring. These are among the first bees out (frequently in May).

References

No information at this time.