Osmia ribifloris

Taxonomy

Family: Megachilidae
Subfamily: Megachilinae
Tribe: Osmiini
Genus: Osmia Panzer, 1806
Subgenus: O. (Osmia) Panzer, 1806
Species: Osmia ribifloris Cockerell, 1900
Common name: none

Overview

Osmia (Osmia) ribifloris are bees with a metallic blue-green body. Females have black hair on the head, thorax, and abdomen (Sandhouse 1939). Males have intermixed black and white hair on their face, scutum, prim, and thorax. They have primarily white hair on T1 to T3 on and primarily dark hair on the remaining terga. Female body length is 10–12 mm, and male body length is 9–10 mm (Rust 1974). O. ribifloris is an important pollinator of blueberries in the U.S. (Torchio 1990).

Diagnostic characteristics 

(from Sandhouse 1939; Rust 1974)

May be confused with 

Osmia ribifloris females can easily be distinguished by the combination of metallic blue to green integument, black hair throughout their body, and relatively simple clypeus that lacks lateral horns or a median emargination. Male O. ribifloris can look similar to O. pedicornis, but they can be differentiated by the shape of the gonocoxites, which are more expanded subapically in O. ribifloris.

Phenology

Osmia ribifloris adults have been recorded in flight during all months except September and November (GBIF 2019g).

Host associations 

Osmia ribifloris specialize in pollinating manzanita (Ericaceae: Arctostaphylos) but are also commonly used to pollinate blueberries (Ericaceae) in commercial landscapes (Torchio 1990).

Nesting behavior 

Osmia ribifloris nests in abandoned Sceliphron nests and in man-made structures, such as drilled holes in wood blocks (Rust 1986; Cane et al. 2007). Cells are arranged in a linear series throughout the nest. Cell partitions and nest plugs are comprised of masticated plant material (Rust 1986).

Distribution

Osmia ribifloris is native to the western and southwestern U.S. (Rust 1974; Russo 2016) and is distributed from Oregon south to Mexico and east to Alabama (GBIF 2019g). Osmia ribifloris was intentionally introduced to Maine in 1991 (Stubbs et al. 1994); however, it is unknown if they have become established there (Russo 2016).


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

<p><em>Osmia ribifloris </em>female face, photo: Chelsey Ritner</p>
Osmia ribifloris female face, photo: Chelsey Ritner
<p><em>Osmia ribifloris </em>female lateral habitus, photo: Chelsey Ritner</p>
Osmia ribifloris female lateral habitus, photo: Chelsey Ritner
<p><em>Osmia ribifloris </em>female abdomen, photo: Chelsey Ritner</p>
Osmia ribifloris female abdomen, photo: Chelsey Ritner
<p><em>Osmia ribifloris </em>male face, photo: Chelsey Ritner</p>
Osmia ribifloris male face, photo: Chelsey Ritner
<p><em>Osmia ribifloris </em>male lateral habitus, photo: Chelsey Ritner</p>
Osmia ribifloris male lateral habitus, photo: Chelsey Ritner
<p><em>Osmia ribifloris </em>male abdomen, photo: Chelsey Ritner</p>
Osmia ribifloris male abdomen, photo: Chelsey Ritner
<p><em>Osmia ribifloris </em>male, diagram showing the genitalia with the dorsal view on the left side and the ventral view on the right, diagram modified from Rust 1974</p>
Osmia ribifloris male, diagram showing the genitalia with the dorsal view on the left side and the ventral view on the right, diagram modified from Rust 1974