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Genus Osmia - Mason Bees

Osmia integra Osmia? - Osmia montana Osmiini 01b - Osmia coloradensis - female bee - Osmia distincta - female Bee house, the next generation - Osmia cornifrons - male Bee - Osmia lignaria - female Metallic green bee - Osmia ribifloris - male Mason Bee - Osmia taurus - male
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Hymenoptera (Ants, Bees, Wasps and Sawflies)
No Taxon (Aculeata - Ants, Bees and Stinging Wasps)
No Taxon (Apoidea (clade Anthophila) - Bees)
Family Megachilidae (Leafcutter, Mason, and Resin Bees, and allies)
Subfamily Megachilinae (Leafcutter, Resin, Mortar, Sharptail, Mason, and Woolcarder bees and relatives)
Tribe Osmiini (Mason bees and relatives)
Genus Osmia (Mason Bees)
Explanation of Names
Osmia Panzer 1806
Numbers
~150 spp. in 9 subgenera our area, >350 spp. in 23 subgenera total(1)
Identification
Metallic green to blue (sometimes all black), with robust body and no pygidial plate(2)
Parapsidal lines are actually small pits rather than lines: arrows

Unique to Osmia is the arolium between the front claws(2):
Range
Holarctic, with 1 sp. ranging into the Neotropics [map](1)
Season
Most species early-late spring, a few active in summer.
(starts flying in Jan. in sw US, in Mar. elsewhere)
Food
Many species visit Vaccinium, including blueberries, and other Ericaceae.
Remarks
Variety of nesting; some excavate in the soil, others use hollow stems, some use abandoned mud wasp nests. They partition the cells with walls made of clay or other materials.
Print References
Cane J.H., Griswold T., Parker F.D. (2007) Substrates and materials used for nesting by North American Osmia bees (Hymenoptera: Apiformes: Megachilidae). Ann. Ent. Soc. Am. 100: 350–358. (Full text)
Michener C.D. (1949) A revision of the American species of Diceratosmia (Hymenoptera, Megachilidae). Ann. Ent. Soc. Am. 42: 258-264. (Full text)
Rust R.W. (1974) The systematics and biology of the genus Osmia, subgenera Osmia, Chalcosmia and Cephalosmia (Hymenoptera: Megachilidae). Wasmann J. Biol. 32: 1-93. (3)
Sandhouse G.A. (1924) Bees of the genus Osmia in the collection of the California Academy of Sciences. Proc. Calif. Acad. Sci. (4) 13: 341-372. (Full text)
Sandhouse G.A. (1939) The North American bees of the genus Osmia. Mem. Ent. Soc. Wash. 1: 1-167. (4)
Sinha R.N. (1958) A subgeneric revision of the genus Osmia in the Western Hemisphere (Hymenoptera: Megachilidae). Kans. Univ. Sci. Bul. 39: 211-261. (Full text)
Sinha R.N., Michener C.D. (1958) A revision of the genus Osmia, subgenus Cetrosmia (Hymenoptera: Megachilidae). Kans. Univ. Sci. Bul. 39: 275-303. (5)
Snelling R.R. (1967) Description of a new subgenus of Osmia (Hymenoptera: Megachilidae). Bull. S.Cal. Acad. Sci. 66: 103-108 (Full text)
White J.R. (1952) A revision of the genus Osmia, subgenus Acanthosmioides (Hymenoptera: Megachilidae). Kans. Univ. Sci. Bul. 35: 219-307. (Full text)
Works Cited
1.Ascher J.S., Pickering J. (2017) Discover Life bee species guide and world checklist (Hymenoptera: Apoidea: Anthophila)
2.The Bees in Your Backyard: A Guide to North America's Bees.
Joseph S. Wilson & Olivia J. Messinger Carril. 2015. Princeton University Press.
3.The systematics and biology of the genus Osmia, subgenera Osmia, Chalcosmia and Cephalosmia
R. W. Rust. 1974. Wasmann Journal of Biology 32(1):1-93.
4.The North American bees of the genus Osmia
G.A. Sandhouse. 1939. Mem. Ent. Soc. Wash. 1: 1-167.
5.A subgeneric revision of the genus Osmia in the Western Hemisphere (Hymenoptera: Megachilidae)
R. N. Sinha . 1958. Kans. Univ. Sci. Bul. Vol. 39, No. 5, pp. 211-261.