The Great Sunflower Project

Exomalopsis – long-horned bees (family Apidae)

Genus summary: Exomalopsis is a small genus restricted to the New World. There are about 85 species total (Michener 2000); most are limited to the tropics but some inhabit the subtropical and desert areas of North America. The genus is more diverse in the western than eastern states (Mitchell 1962).

Floral relationships: Exomalopsis are floral generalists. Males commonly search for mates at flowers (O’Toole & Raw 1999).

Nesting habits: Exomalopsis are communal nesters; two or more queens share a nest but build and provision their own brood cells. Hundreds of females may inhabit one nest, each provisioning their own cells. Subsequent generations of queens return to the same nest year after year, thus adding to its size. Some species are semi-social and females cooperatively provide for each other’s brood cells (Michener 2000). Brood cells are lined with a “waxlike” material that is secreted by the female (O’Toole & Raw 1999).

Diagnostic characteristics: Exomalopsis are tiny to moderate sized bees between 0.2 to 0.5 inches long that are robust and hairy (Michener 2000). Females have dense, feathery pollen scopae (brushes of hair) on the lower parts of their hind legs (Mitchell 1962). They have pale bands of hair on their abdomen (Michener 2000), which is sometimes red. Males have very long antennae .
Similar taxa: Other Eucerini, such as Diadasia, Peponapis & Svastra

Known conservation concerns:

Interesting Fact: Zucchi (1973) found 884 females in one nest that was 5 ½ yards deep!

Additional resources:

Worldwide map of Exomalopsis

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