The Great Sunflower Project

Photo by Bill Claff
Ceratina - small carpenter bees (family Apidae)
by Lisa Schonberg and Mace Vaughan (Xerces Society) and Gretchen LeBuhn (SFSU)

Genus summary: The genus Ceratina is found on all continents except Antarctica (Michener 2000). There are 21 species of Ceratina that are common in the U.S. and Canada. Ceratina is rare in desert habitats (Michener 1994).
Floral relationships: Most Ceratina spp. are generalist foragers and are found on a wide variety of plant species .
Nesting habits: Ceratina includes solitary species and social species (O’Toole & Raw 1999). While commonly called carpenter bees, they usually excavate their nests in the pithy centers of dead stems rather than in wood. Some of the shrubs they commonly use for nesting are elderberry, box elder, sumac, Rubus spp. and Helianthus spp. .
Diagnostic characteristics: Ceratina are closely related to the genus Xylocopa (the large carpenter bees), but they are much smaller and flatter. Ceratina are small, 0.1 to 0.6 inches long, shiny, sturdy, sparsely haired and black, blue or green (Michener 1994, 2000). The tip of their abdomen is shield-like in shape. Most species have yellow markings on the face and females often have a yellow bar in the middle of their face below their antennae . Females carry dry pollen on scopa (brushes of hair) on their hind legs .
Similar taxa: May be confused with shiny dark bees in the family Halictidae, but Ceratina is distinguished by the lack of pollen hairs on its femur (the part of the leg closest to the bee’s body).
Known conservation concerns:
Interesting fact: This group is unusual because it has several species that are parthenogenetic: females can produce eggs without mating. One of the best known parthenogenetic species is Ceratina dalletorreana, a species native to Europe which has been introduced to California .
Additional resources: Daly (1973)

Key to Eastern Ceratina at Discover Life