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 1939Sandhouse 1939:
Sandhouse, G.A. 1939. The North American bees of the genus Osmia (Hymenoptera: Apoidea). The Entomological Society of Washington, Washington, D.C.: 1ndash;172.). Males have intermixed black and white hair on their face, scutumscutum:
the large segment on top of the thorax located between the wings and behind the head
, prim, and thorax. They have primarily white hair on T1T1:
the segments on the top side of the abdomen, often abbreviated when referring to a specific segment to T1, T2, T3, T4, T5, T6, or T7
to T3T3:
the segments on the top side of the abdomen, often abbreviated when referring to a specific segment to T1, T2, T3, T4, T5, T6, or T7
on and primarily dark hair on the remaining tergaterga:
the segments on the top side of the abdomen, often abbreviated when referring to a specific segment to T1, T2, T3, T4, T5, T6, or T7
. Female body length is 10–12 mm, and male body length is 9–10 mm (Rust 1974Rust 1974:
Rust, R.W. 1974. The systematics and biology of the genus Osmia, subgenera Osmia, Chalcosmia, and Cephalosmia. Wasmann Journal of Biology 32: 1ndash;93.). O. ribifloris is an important pollinator of blueberries in the U.S. (Torchio 1990Torchio 1990:
Torchio, P.F. 1990. Osmia ribifloris , a native bee species developed as a commercially managed pollinator of highbush blueberry (Hymenoptera: Megachilidae). Journal of the Kansas Entomological Society 63: 427ndash;436.).

Diagnostic characteristics 

(from Sandhouse 1939Sandhouse 1939:
Sandhouse, G.A. 1939. The North American bees of the genus Osmia (Hymenoptera: Apoidea). The Entomological Society of Washington, Washington, D.C.: 1ndash;172.; Rust 1974Rust 1974:
Rust, R.W. 1974. The systematics and biology of the genus Osmia, subgenera Osmia, Chalcosmia, and Cephalosmia. Wasmann Journal of Biology 32: 1ndash;93.)

• Mouthparts usually much smaller than the length of the entire body when extended.
• Terga terga:
  the segments on the top side of the abdomen, often abbreviated when referring to a specific segment to T1, T2, T3, T4, T5, T6, or T7
  without apicalapical:
  near or at the apex or end of any structure
  hair bandsbands:
  usually referring to bands of hair or bands of color that traverse across an abdominal segment
  .
• Female clypeusclypeus:
  a section of the face below the antennae, demarcated by the epistomal sutures
  without laterallateral:
  relating, pertaining, or attached to the side
  horns or median emarginationemargination:
  a notched or cut out place in an edge or margin, can be dramatic or simply a subtle inward departure from the general curve or line of the margin or structure being described
  . .
• Female malar spacemalar space:
  the shortest distance between the base of the mandible and the margin of the compound eye
  without a projection.
• Female mandibles have a complete cutting edge and medial teeth.
• Female scopal hairscopal hair:
  modified hairs for carrying pollen; often branched and dense hairs on the hind-leg, or on the ventral surface of the abdomen in Megachilidae
  black.
• Male hind basitarsusbasitarsus:
  the segment of the tarsus that is the nearest to the body of the bee, usually the largest of all the tarsal segments
  without a ventralventral:
  of, on, or relating to the underside of an animal, or segment of an animal
  tooth.
• Male gonocoxites slightly expanded subapically.
• Male T7T7:
  the segments on the top side of the abdomen, often abbreviated when referring to a specific segment to T1, T2, T3, T4, T5, T6, or T7
  medially emarginateemarginate:
  a notched or cut out place in an edge or margin, can be dramatic or simply a subtle inward departure from the general curve or line of the margin or structure being described
  .

May be confused with 

Osmia ribifloris females can easily be distinguished by the combination of metallic blue to green integumentintegument:
a tough, protective outer layer
, black hair throughout their body, and relatively simple clypeusclypeus:
a section of the face below the antennae, demarcated by the epistomal sutures
that lacks laterallateral:
relating, pertaining, or attached to the side
horns or a median emarginationemargination:
a notched or cut out place in an edge or margin, can be dramatic or simply a subtle inward departure from the general curve or line of the margin or structure being described
. 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 2019gGBIF 2019g:
GBIF.org . 12 July 2019. GBIF Occurrence Download. https://doi.org/10.15468/dl.g5ar8l).

Host associations 

Osmia ribifloris specialize in pollinating manzanita (Ericaceae: Arctostaphylos) but are also commonly used to pollinate blueberries (Ericaceae) in commercial landscapes (Torchio 1990Torchio 1990:
Torchio, P.F. 1990. Osmia ribifloris , a native bee species developed as a commercially managed pollinator of highbush blueberry (Hymenoptera: Megachilidae). Journal of the Kansas Entomological Society 63: 427ndash;436.).

Nesting behavior 

Osmia ribifloris nests in abandoned Sceliphron nests and in man-made structures, such as drilled holes in wood blocks (Rust 1986Rust 1986:
Rust, R.W. 1986. Biology of Osmia (Osmia) ribifloris Cockerell (Hymenoptera: Megachilidae). Journal of the Kansas Entomological Society 59 (1): 89ndash;94.; Cane et al. 2007Cane et al. 2007:
Cane, J.H., T. Griswold, and F.D. Parker. 2007. Substrates and materials used for nesting by North American Osmia bees (Hymenoptera: Apiformes: Megachilidae). Annals of the Entomological Society of America 100: 350ndash;358.). Cells are arranged in a linear series throughout the nest. Cell partitions and nest plugs are comprised of masticated plant material (Rust 1986Rust 1986:
Rust, R.W. 1986. Biology of Osmia (Osmia) ribifloris Cockerell (Hymenoptera: Megachilidae). Journal of the Kansas Entomological Society 59 (1): 89ndash;94.).

Distribution

Osmia ribifloris is native to the western and southwestern U.S. (Rust 1974Rust 1974:
Rust, R.W. 1974. The systematics and biology of the genus Osmia, subgenera Osmia, Chalcosmia, and Cephalosmia. Wasmann Journal of Biology 32: 1ndash;93.; Russo 2016Russo 2016:
Russo, L. 2016. Positive and negative impacts of non-native bee species around the world. Insects 7: 69.) and is distributed from Oregon south to Mexico and east to Alabama (GBIF 2019gGBIF 2019g:
GBIF.org . 12 July 2019. GBIF Occurrence Download. https://doi.org/10.15468/dl.g5ar8l). Osmia ribifloris was intentionally introduced to Maine in 1991 (Stubbs et al. 1994Stubbs et al. 1994:
Stubbs, C.S., F.A. Drummond, and E.A. Osgood. 1994. Osmia ribifloris biedermannii and Megachile rotundata (Hymenoptera: Megachilidae) introduced into the lowbush blueberry agroecosystem in Maine. Journal of the Kansas Entomological Society 67: 173ndash;185.); however, it is unknown if they have become established there (Russo 2016Russo 2016:
Russo, L. 2016. Positive and negative impacts of non-native bee species around the world. Insects 7: 69.).

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

References

Cane, J.H., T. Griswold, and F.D. Parker. 2007. Substrates and materials used for nesting by North American Osmia bees (Hymenoptera: Apiformes: Megachilidae). Annals of the Entomological Society of America 100: 350-358.

GBIF.org . 12 July 2019. GBIF Occurrence Download https://doi.org/10.15468/dl.g5ar8l

Russo, L. 2016. Positive and negative impacts of non-native bee species around the world. Insects 7: 69.

Rust, R.W. 1974. The systematics and biology of the genus Osmia, subgenera Osmia, Chalcosmia, and Cephalosmia (Hymenoptera: Megachilidae). Wasmann Journal of Biology 32: 1-93.

Rust, R.W. 1986. Biology of Osmia (Osmia) ribifloris Cockerell (Hymenoptera: Megachilidae). Journal of the Kansas Entomological Society 59(1): 89-94.

Sandhouse, G.A. 1939. The North American bees of the genus Osmia (Hymenoptera: Apoidea). The Entomological Society of Washington, Washington, D.C.: 1-172.

Stubbs, C.S., F.A. Drummond, and E.A. Osgood. 1994. Osmia ribifloris biedermannii and Megachile rotundata (Hymenoptera: Megachilidae) introduced into the lowbush blueberry agroecosystem in Maine. Journal of the Kansas Entomological Society 67: 173-185.

Torchio, P.F. 1990. Osmia ribifloris, a native bee species developed as a commercially managed pollinator of highbush blueberry (Hymenoptera: Megachilidae). Journal of the Kansas Entomological Society 63: 427-436.