European small-woolcarder (Pseudoanthidium nanum)

Megachilidae > Pseudoanthidium > Pseudoanthidium nanum

European small-woolcarder (Psuedoanthidium nanum) is found on small weedy asters growing in cracks in the sidewalk. This exotic species thrives in the most industrial and urbanized places. P. nanum is a recent arrival in the northeast, but has since spread to major population centers along the eastern seaboard.


June through September. One, possibly two generations per year.


Widespread, and continuing to spread throughout northeast since first detection in New Jersey in 2008. Concentrated in cities, including Boston, Massachusetts; Providence; Rhode Island; New York, New York; and Philadelphia, PA.


Size << honey bee

Females are a tiny anthidiine with dark eyes. Yellow paroculars and black clypeus. Rough textured integument does not reflect sunlight. Cream-colored ovals on edges of tergites. Bright orange legs. Transparent wings held down while foraging.

Males are similar to females but with yellow clypeus and yellow paroculars.

Similar species

  • Anthidium oblongatum has green eyes, orange tegulae, and broken yellow bands) on abdomen. A. oblogatum is often found in weedy agricultural fields with flowering legumes, in which P. nanum does not seem to occur.
  • Anthidiellum notatum has smoother, more reflective integument, dark wings, and bright yellow markings on abdomen.


Above-ground in a variety of cavities including hollow stems, and crevices in buildings and bricks.


Asteraceae, especially smaller composites like fleabane Erigeron spp., coreopsis Coreopsis, and knapweed Centaurea.

Natural Enemies

Information on natural enemies in North American range is missing.


Portman, Z.M., Burrows, S.J., Griswold, T.G., and Arduser, M. 2019. First Records of the Adventive Pseudoanthidium nanum (Mocsáry) (Hymenoptera: Megachilidae) in Illinois and Minnesota, with Notes on its Identification and Taxonomy. The Great Lakes Entomologist. 52: 12-20.

Page last updated:
January 17, 2023