The Great Sunflower Project

Photo by Hartmut Wisch

Anthidium – carder bees (family Megachilidae)
by Lisa Schonberg and Mace Vaughan (Xerces Society) and Gretchen LeBuhn (SFSU)

Genus summary- The genus Anthidium is found on all continents except Australia. There are about 23 species in the U.S. and Canada (Michener 2000), with the highest diversity in southwestern U.S. deserts. Anthidium are commonly called “carder bees” because they card (comb) cottony down from hairy leaves to line their nest cells with. The female’s mandibles have five sharp teeth and are used like a comb to remove hairs from leaves (O’toole & Raw 1999).

Nesting habits- Anthidium make their nests from plant hairs in pre-existing burrows in soil, walls, wood and stems, or they dig their nests in loose soil in the ground (Michener 2000).

Diagnostic characters: Anthidium have very distinctive color patterns; most species have a conspicuous pattern of yellow abdominal bands that are interrupted in the middle on a black background. They are robust and moderate sized, 0.3 to 0.8 inches long. Their abdomen is broad and somewhat flattened (Michener 2000). Anthidium females carry dry pollen on scopa (brushes of hairs) on the underside of the abdomen rather than on their hind legs like most bees (O’Toole & Raw 1999). This is characteristic of all females in the family Megachilidae, which also includes Megachile, Osmia, and Hoplitis. Male Anthidium are larger than females.

Similar taxa: Anthidium can be mistaken for wasps but are generally more robust.

Known conservation concerns: One species in this genus, Anthidium manicatum, is native to Europe and has been introduced to North and South America. It is range is quickly spreading, and has been collected in Connecticut, Nova Scotia, Ohio and Michigan (Hoebeke & Wheeler 2005, Maier 2005, Miller et al.. 2002). the spread of Anthidium manicatum may be detrimental to native bees because the males of the species aggressively defend their territory and even kill intruders (Wirtz 1988).

Additional resources: Grigarick & Stange (1968)

Key to Eastern Anthidium at DiscoverLife