Osmia (Osmia) excavata are black bees with a green luster to their abdomen (Wei et al. 2002). Females have intermixed white and black hair on the head and thorax, yellow to black hair on the discs of T1–T6, and pale apical hair bands on the terga (Wu 2006). Female length ranges between 9–13 mm, and male body length ranges between 8–10 mm. (Wei et al. 2002; Wu 2006). O. excavata is an important fruit tree pollinator in Japan and is considered an ideal species for apple pollination (Wei et al. 2002).
(modified from Wu 2006)
Female Osmia excavata are most similar to O. fedtschenkoi because of the deep triangular-shaped emargination on the clypeus. The emargination of O. excavata, however, continues into the disc of the clypeus, creating a shiny-bottomed concavity which differs from the more simple triangular emargination 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 emargination on the apical rim of the clypeus of O. excavata as well as by the shape of the gonocoxites.
Osmia excavata adults have been recorded in flight from late March to early April (Wei et al. 2002).
Osmia excavata appear to prefer plants from the Rosaceae family (Wei et al. 2002).
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 1978).
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 2006).