Osmia excavata

Taxonomy

Family: Megachilidae
Subfamily: Megachilinae
Tribe: Osmiini
Genus: Osmia Panzer, 1806
Subgenus: O. (Osmia) Panzer, 1806
Species: Osmia excavata Alfken, 1903
Common name: none

Overview

Osmia (Osmia) excavata are black bees with a green luster to their abdomen (Wei et al. 2002Wei et al. 2002:
Wei, S.G., Wang, R., Smirle, M.J., Xu, H.L. 2002. Release of Osmia excavata and Osmia jacoti (Hymenoptera: Megachilidae) for apple pollination. Canadian Entomologist 134: 369ndash;380.). Females have intermixed white and black hair on the head and thorax, yellow to black hair on the discs of T1–T6, and pale 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
on the 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
(Wu 2006Wu 2006:
Wu, Y. 2006. Hymenoptera: Megachilidae. Fauna Sinica, Insecta. Vol. 4. Science Press, Beijing.). Female length ranges between 9–13 mm, and male body length ranges between 8–10 mm. (Wei et al. 2002Wei et al. 2002:
Wei, S.G., Wang, R., Smirle, M.J., Xu, H.L. 2002. Release of Osmia excavata and Osmia jacoti (Hymenoptera: Megachilidae) for apple pollination. Canadian Entomologist 134: 369ndash;380.; Wu 2006Wu 2006:
Wu, Y. 2006. Hymenoptera: Megachilidae. Fauna Sinica, Insecta. Vol. 4. Science Press, Beijing.). O. excavata is an important fruit tree pollinator in Japan and is considered an ideal species for apple pollination (Wei et al. 2002Wei et al. 2002:
Wei, S.G., Wang, R., Smirle, M.J., Xu, H.L. 2002. Release of Osmia excavata and Osmia jacoti (Hymenoptera: Megachilidae) for apple pollination. Canadian Entomologist 134: 369ndash;380.).

Diagnostic characteristics 

(modified from Wu 2006Wu 2006:
Wu, Y. 2006. Hymenoptera: Megachilidae. Fauna Sinica, Insecta. Vol. 4. Science Press, Beijing.)

• Mouthparts 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
  present.
• Female clypeusclypeus:
  a section of the face below the antennae, demarcated by the epistomal sutures
  deeply excavated forming a triangular-shaped concavity with a shiny bottom.
• 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
  yellowish-red.
• Male clypeusclypeus:
  a section of the face below the antennae, demarcated by the epistomal sutures
  without 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 strigilisstrigilis:
  an organ for cleaning the antennae on the first tarsal joint of a bee's foreleg
  with small apicalapical:
  near or at the apex or end of any structure
  spine.
• 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
  truncate medially.

May be confused with 

Female Osmia excavata are most similar to O. fedtschenkoi because of the deep triangular-shaped 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
on the clypeusclypeus:
a section of the face below the antennae, demarcated by the epistomal sutures
. The 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
of O. excavata, however, continues into the discdisc:
a generic term for the middle surface of a plate (usually in reference to an abdominal segment)
of the clypeusclypeus:
a section of the face below the antennae, demarcated by the epistomal sutures
, creating a shiny-bottomed concavity which differs from the more simple triangular 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
of O. fedtschenkoi. Male O. excavata can look very similar to O. longicornis, but they can be distinguished by the lack of a distinct 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
on the apicalapical:
near or at the apex or end of any structure
rim of the clypeusclypeus:
a section of the face below the antennae, demarcated by the epistomal sutures
of O. excavata as well as by the shape of the gonocoxites.

Phenology

Osmia excavata adults have been recorded in flight from late March to early April (Wei et al. 2002Wei et al. 2002:
Wei, S.G., Wang, R., Smirle, M.J., Xu, H.L. 2002. Release of Osmia excavata and Osmia jacoti (Hymenoptera: Megachilidae) for apple pollination. Canadian Entomologist 134: 369ndash;380.).

Host associations 

Osmia excavata appear to prefer plants from the Rosaceae family (Wei et al. 2002Wei et al. 2002:
Wei, S.G., Wang, R., Smirle, M.J., Xu, H.L. 2002. Release of Osmia excavata and Osmia jacoti (Hymenoptera: Megachilidae) for apple pollination. Canadian Entomologist 134: 369ndash;380.).

Nesting behavior 

Osmia excavata nests in preexisting cavities, typically in insect borings in dead wood, as well as in hollow plants, stems of bamboo, and straw tubes. Cell wall, partitions, and nest plug are composed of mud or leaf materials (Maeta 1978Maeta 1978:
Maeta, Y. 1978. Comparative studies on the biology of the bees of the genus Osmia of Japan, with special reference to their managements for pollinations of crops (Hymenoptera: Megachilidae). Bulletin of the Tohoku National Agricultural Experiment Station. 57: 195ndash;209.).

Distribution

Osmia excavata specimens have been recorded in Beijing, Hebei, Liaoning, Shanghai, Jiangsu, and Shandong in China, as well as in Japan and the North Korean peninsula (Wu 2006Wu 2006:
Wu, Y. 2006. Hymenoptera: Megachilidae. Fauna Sinica, Insecta. Vol. 4. Science Press, Beijing.).

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

References