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University of Minnesota Extension

Species guide - species detail

Osmia georgica (Mason bee)



Bees in the genus Osmia, in the family Megachilidae, are known as mason bees because some of them use mud to build their nests. 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. This is one of several smaller Osmia species. Osmia georgica was recorded in our state for the first time through the Bee Atlas project, in the 2018 blocks!


Osmia georgica have a typical blue metallic exoskeleton and look similar to Osmia pumila at first glance. Female Osmia georgica have distinctive yellow scopal hair under the abdomen.

Nest Structure

The Bee Atlas nest was plugged with chewed vegetation material, the same material as recorded in the literature (eg. Hawkins 1975, and Hartman et al. 1944).

Hole Sizes

The single Bee Atlas nests was found in a 3/16" hole (lower column 3). Hawkins (1975) reported 12 nests in 1/4" holes (but did not offer smaller diameters). Hartman et al. (1944) recorded nests in 4-5mm tunnels, which are a little smaller and a little larger than 3/16" respectively.


Univoltine, meaning they complete one generation per year in Minnesota. Both males and females overwinter as adults inside their cocoons. Hawkins (1975) also reported univoltine lifecycles for Tennessee.

Activity Period

Early spring. Osmia are among the first bees of the year (frequently in May).


___(1)__Hawkins 1975. NESTING BIOLOGY OF OSMIA (CHALCOSMIA) GEORGICA (HYMENOPTERA: MEGACHILIDAE). Journal of the Kansas Entomological Society, 48(4): 493-499. ___(2)___Hartman, C. G., P. Hartman, P. Hartman and C. Retenmeyer. 1944. Note on the habits of Osmia georgica Cresson as ascertained by the glass-tube method. Psyche 51:162-165.

Minnesota Record Map

These data are from the Minnesota Bee Atlas project.

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