Osmia cornifrons


Family: Megachilidae
Subfamily: Megachilinae
Tribe: Osmiini
Genus: Osmia Panzer, 1806
Subgenus: O. (Osmia) Panzer, 1806
Species: Osmia cornifrons Radoszkowski, 1887
Common name: Japanese hornfaced bees


Osmia (Osmia) cornifrons are black bees with a copper luster (Wu 2006). Females have light yellow hair on the thorax and T1T3; T4T6 are covered with dark brown hair (Wu 2006). Males primarily have pale hair on their head, thorax, and abdomen, often with black hairs intermixed (Wu 2006). Female body length ranges from 8–12 mm, and male body length ranges from 8–10 mm (Wu 2006). O. cornifrons is used worldwide as a pollinator of commercial crops, especially apple trees, and was successfully introduced to the U.S. in the 1970s (Batra 1978).

Diagnostic characteristics 

(modified from Yasumatsu and Hirashima 1950; Wu 2006)

  • Mouthparts much smaller than the length of the entire body when extended.
  • Terga usually with loosely formed apical hair bands.
  • Female clypeus disc with the apical half shiny and impunctate and the basal half densely punctate.
  • Female clypeus with long lateral horns and an acute median apical projection.
  • Female mandible with inner-most tooth at almost a right angle.
  • Female scopa reddish-brown.
  • Male antenna with F1 shorter than F2.
  • Male clypeus irregularly notched medially.
  • Male gonostylus distinctly expanded subapically.
  • Male S2 large, often covering S3 to S4.
  • Male T6 and T7 without median emargination.

May be confused with 

Osmia cornifrons look similar enough to O. taurus that it likely led to the accidental introduction of O. taurus to the U.S. Osmia cornifrons can be differentiated from O. taurus by the acute inner tooth of the mandible and the densely punctate basal half of the clypeus in O. cornifrons (Yasumatsu and Hirashima 1950). Males can be more difficult to differentiate, but O. taurus tend to have abdominal hair with a distinct red to orange hue, which can be faded in older specimens, and O. cornifrons have pale white abdominal hair, sometimes with black hair intermixed. The gonocoxites of O. cornifrons are also distinctly expanded subapically compared to the only slightly expanded gonocoxites of O. taurus.


Osmia cornifrons have been recorded in flight in the U.S from March to June, with the majority of occurrences through April. In Asia, specimens have been recorded from January to August (GBIF 2019b).

Host associations 

Osmia cornifrons are a polylectic species and have been observed visiting plants within the families Rosaceae, Ericaceae, Caprifoliaceae, Aceraceae, Leguminosae, Fabaceae, and Brassicaceae, with a preference for Rosaceae (Maeta 1978; Quest 2009; Haider et al. 2013). O. cornifrons are also important pollinators for fruit crops and are commonly used commercially for the pollination of apple orchards (Matsumoto and Maejima 2010).

Nesting behavior 

Osmia cornifrons is a solitary bee that nests in preexisting cavities. In the New World, nests can be found in reeds, bamboo, holes within trees, insect borings in dead wood, and hollow stems, and in the Old World, nests can be found in cracks in bark, and cracks or crevices in rock (Maeta 1978). Nests cells are constructed of mud and leaf pulp (Maeta 1978). O. cornifrons will forage up to 130 m from the nesting site (Kitamura 1974).


Osmia cornifrons is native to eastern Asia and has been found in Japan and Korea as well as the southeast coast of Russia (Yasumatsu and Hirashima 1950). O. cornifrons was intentionally introduced to the eastern U.S. from Japan in the 1970s to increase crop pollination (Batra 1979). In the U.S., O. cornifrons can be found on the East Coast and the Midwest (GBIF 2019b).

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

<p>Fig 1, <em>Osmia cornifrons</em> female face, photo: Chelsey Ritner</p>
Fig 1, Osmia cornifrons female face, photo: Chelsey Ritner
<p>Fig 2, <em>Osmia cornifrons</em> female lateral habitus, photo: Chelsey Ritner</p>
Fig 2, Osmia cornifrons female lateral habitus, photo: Chelsey Ritner
<p>Fig 3, <em>Osmia cornifrons</em> female abdomen, photo: Chelsey Ritner</p>
Fig 3, Osmia cornifrons female abdomen, photo: Chelsey Ritner
<p>Fig 4, <em>Osmia cornifrons</em> male face, photo: Chelsey Ritner</p>
Fig 4, Osmia cornifrons male face, photo: Chelsey Ritner
<p>Fig 5, <em>Osmia cornifrons</em> male lateral habitus, photo: Chelsey Ritner</p>
Fig 5, Osmia cornifrons male lateral habitus, photo: Chelsey Ritner
<p>Fig 6, <em>Osmia cornifrons</em> abdomen, photo: Chelsey Ritner</p>
Fig 6, Osmia cornifrons abdomen, photo: Chelsey Ritner
<p>Fig 7, <em>Osmia cornifrons </em>male, diagram showing dorsal view of genitalia, diagram modified from Rust 1974</p>
Fig 7, Osmia cornifrons male, diagram showing dorsal view of genitalia, diagram modified from Rust 1974