Family: Megachilidae
Subfamily: Megachilinae
Tribe: Osmiini
Genus: Atoposmia Cockerell, 1935
Subgenera: Atoposmia, Eremosmia, Hexosmia
Common name: none


Atoposmia are robust bees that range in body length from 5.5–9 mm (Michener 2007). They typically have black bands with white bands of hair on their terga, and white or off-white hair on the face and thorax (Michener 2007). Members of the subgenus Hexosmia have a slightly metallic green coloration on the head, thorax, and abdomen (Michener 2007).


Atoposmia contains approximately 30 species that are known from North America (Hurd and Michener 1955; Wilson and Carril 2016).

Diagnostic characteristics

(modified from Michener 2007)

May be confused with

Atoposmia may be confused with Hoplitis and Ashmeadiella due to their similar dark-colored bodies with relatively stocky builds. Ashmeadiella has a carinate omaulus which differentiates it from Atoposmia, while Hoplitis are often more slender, and the males have basal flaps on S6 (Michener 2007).

Known invasives

There are no known invasives.

Host associations

Most species of Atoposmia are specialists on Penstemon spp. (Michener 1949; Crosswhite and Crosswhite 1966; Tepedino et al. 2007; Wilson et al. 2010; Scott et al. 2011).

Nesting behavior

Some members of subgenus Atoposmia make nests under rocks or in rock crevices as single cell clusters. Nest partitions are comprised of masticated plant material with the occasional inclusion of sand (Parker 1975, 1977). Members of subgenus Eremosmia can be found nesting in hollow stems or in the soil, where they construct nests of masticated plant material, soil, or a combination of the two reinforced with nectar (Parker 1975, 1977; Yanega 1994). Members within the subgenus Hexosmia nest in stems, with cell walls built out of chewed plant material with the occasional inclusion of sand (Parker 1975).


Atoposmia is endemic to North America and occurs from British Colombia, Canada to Puebla, Mexico (Michener 2007). They are most diverse in the western U.S., especially in montane environments (subgenus Atoposmia) and deserts (subgenus Eremosmia). A few species occur eastward to west Texas and Oklahoma (Michener 2007; Wilson and Carril 2016). In the US, they are predominantly spring bees, while in Mexico, they fly in the fall (Wilson and Carril 2016).

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<p><em>Atoposmia</em> aff. <em>daleae</em> male face, photo: C. Ritner</p>
Atoposmia aff. daleae male face, photo: C. Ritner
<p><em>Atoposmia</em> aff. <em>daleae</em> male lateral habitus, photo: C. Ritner</p>
Atoposmia aff. daleae male lateral habitus, photo: C. Ritner
<p><em>Atoposmia </em>aff. <em>daleae </em>male abdomen, hoto: C. Ritner</p>
Atoposmia aff. daleae male abdomen, hoto: C. Ritner