Osmia (Diceratosmia)


Family: Megachilidae
Subfamily: Megachilinae
Tribe: Osmiini
Genus: Osmia Panzer, 1806
Subgenus: Diceratosmia Robertson, 1903
Common name: none


Osmia (Diceratosmia) are metallic blue or green bees with mostly pale pubescence, including scopal hairs, which can be white, golden, or reddish-golden (Griswold and Rightmyer 2017). They range in body length from 4–8 mm (Michener 2007).

Diagnostic characteristics

(modified from Griswold and Rightmyer 2017, unless otherwise stated)

May be confused with

Osmia (Diceratosmia) may be confused with O. (Pyrosmia) due to similar characters such as carinate posterior margin of the male S4, carinate hind coxae in females, short pale pubescence, and elongate parapsidal lines (Michener 2007). However, these subgenera can be differentiated by the hind coxae being extremely carinate in both sexes of O. (Diceratosmia), whereas it is less carinate in male O. (Pyrosmia) (Michener 2007). Additionally, O. (Diceratosmia) lacks a median groove on the S6, which is present in O. (Pyrosmia) (Michener 2007).

Host associations

Osmia (Diceratosmia) have been observed visiting Asteraceae, Lamiaceae, Nyctaginaceae, Brassicaceae, Rubiaceae, Fabaceae, Boraginaceae, Cactaceae, Malvaceae, Arecaceae, Anacardiaceae, Plantaginaceae, Portulacaceae, Rhamnaceae, Rosaceae, Salicaceae, Solanaceae, and Zygophyllaceae (Dieringer et al. 1991; Griswold and Rightmyer 2017). One species of Diceratosmia, Osmia conjunctoides, was observed visiting Crotalaria pumila (Rightmyer et al. 2011).

Nesting behavior

Osmia (Diceratosmia) have been observed nesting in snail shells, beetle burrows, and leaf pulp rolled in the sand (Rau 1937; Linsley 1946; Mitchell 1962; Krombein 1967; Neff and Simpson 1992; Griswold and Rightmyer 2017). Osmia (Diceratosmia) is the only Osmia subgenus in the Western Hemisphere that is known to nest in snail shells (Cane et al. 2007; Griswold and Rightmyer 2017).


Osmia (Diceratosmia) contains eleven species (Griswold and Rightmyer 2017).

Known invasives

There are no known invasives.


Osmia (Diceratosmia) is endemic to North America and can be found from Costa Rica to southeastern Canada, with most species occurring in southern U.S. and Mexico (Griswold and Rightmyer 2017).

Dicertosmia Distribution
​Distribution map generated by Discover Life -- click on map for details, credits, and terms of use.

<p><em>Osmia aliciae </em>female face, photo: Chelsey Ritner</p>
Osmia aliciae female face, photo: Chelsey Ritner
<p><em>Osmia aliciae </em>female lateral habitus, photo: Chelsey Ritner</p>
Osmia aliciae female lateral habitus, photo: Chelsey Ritner
<p><em>Osmia aliciae </em>female abdomen, photo: Chelsey Ritner</p>
Osmia aliciae female abdomen, photo: Chelsey Ritner