Osmia (Pyrosmia)


Family: Megachilidae
Subfamily: Megachilinae
Tribe: Osmiini
Genus: Osmia Panzer, 1806
Subgenus: Pyrosmia Tkalců, 1975
Common name: none


Osmia (Pyrosmia) are bees with metallic blue, green, purple, or red integument and pale or sometimes red pubescence. They often have apical bands of hair on the terga and range in body length from 4–8 mm (Michener 2007).

Diagnostic characteristics

(modified from Michener 2007)

  • Hind coxa with a longitudinal carina along inner ventral angle, which can be weak and difficult to see at times.
  • Female clypeus is truncate and overhangs the base of the labrum.
  • Female mandibles are robust and narrower medially than basally.
  • Male S4 apical margin has two carinae laterally with a narrow, hairless, shiny groove between them.
  • Male S6 with a longitudinal median groove.
  • Male T6 margin medially convex and often somewhat inflated laterally.
  • Male T7 is often trifid.

May be confused with

Osmia (Pyrosmia) are often similar looking to O. (Diceratosmia). These two subgenera have enough shared characters that it has been suggested that they could be combined into a single subgenus (Michener 2007). Some of the notable characters they have in common are the two lateral carina on the apical margin of the male S4, carinate hind coxae, and elongate parapsidal lines (Michener 2007). Osmia (Pyrosmia) males can be differentiated from O. (Diceratosmia) by their simple, gently convex T6 and the longitudinal median groove on S6 (Michener 2007). Females can be more difficult to tell apart but Osmia (Pyrosmia) often have weaker carina on the hind coxa.

Host associations

Osmia (Pyrosmia) are generalists with a preference for Fabaceae, Asteraceae, Boraginaceae, Lamiaceae, Resedaceae, Antirrhineae, Brassicaceae, Cistaceae, Alliaceae, Crassulaceae, and Campanulaceae (Banaszak and Romasenko 1998; Grace 2010; Khodaparast and Monfared 2012, 2013; Müller 2018b).

Nesting behavior

Species of Osmia (Pyrosmia) have been observed nesting in holes in wood, stems, galls, abandoned insect burrows, cavities between stones, and snail shells (Michener 2007, Müller 2018b). Cell partitions are constructed out of leaf pulp (Michener 2007). Osmia amathusica nests in crevices in stones. Cells are constructed out of masticated leaves and small pebbles (Müller 2018b). Osmia cyanoxantha nests in preexisting cavities and on stone surfaces in small holes. Cell partitions are comprised of masticated leaves and occasionally small pebbles. Nest plugs are constructed from 2–4 layers small pebbles and leaf pulp (Müller 2018b). Osmia derasa nests in the abandoned cells of Hoplitis nests (Müller 2018b). Osmia ferruginea nests in empty snail shells and hollow stems. Cell partitions and nest plugs are comprised of masticated leaves, with the occasional use of small pebbles or other particles. The space between the outer cell and the nest plug is filled with pebbles, dirt, seeds, or leaflets (Müller 2018b). Osmia oramara nest in cavities between flat stones. Cells are constructed of leaf pulp. The cells are attached to one another with the use of leaf pulp and masticated leaves. The cell chamber is covered in leaf pulp (Müller 2018b). Osmia submicans nests in insect burrows in dead wood, hollow stems, cavities in small rocks, and abandoned cells in Megachile nests. Cell partitions are comprised of masticated leaves. Nest plugs are constructed from leaf pulp and occasionally small pebbles or mud (Müller 2018b).


Osmia (Pyrosmia) consists of 30 species (Müller 2018b). None are known to occur in the U.S. or Canada.

Known invasives

There are no known invasives.


Osmia (Pyrosmia) ranges from central and southern Europe, the Mediterranean Basin, India, and Mongolia (Michener 2007).

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

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