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Colletes

Colletes – polyester bees/digger bees (family Colletidae)
By Lisa Schonberg and Mace Vaughan (Xerces Society and Gretchen LeBuhn (SFSU)

Genus summary: Colletes is a widespread and common genus that occurs worldwide with the exception of Indonesia and Australia. In North America Colletes range as far north as Alaska. There are 90 species in North and Central America (Michener 2000), and about 20 in New York State (Danforth & Magnacca 2002) and 20 in the northwestern portion of the U.S. and Canada (Stephen et al 1969).
Floral relationships: Many Colletes spp. are specialist foragers, visiting flowers on only a small number of plant species. They are limited to certain flower shapes because they have short tongues (O’Toole & Raw 1999).

Nesting habits: Most Colletes are solitary ground nesting bees, and a few ground-nesting species nest in large aggregations (Michener 1994). They are called “polyester bees” because of their unique method of lining their brood cells with a completely waterproof cellophane-like material that they secrete. The cellophane-like material does not permeate the surrounding soil; it is instead easily separable from the soil. A Colletes female completely encloses her brood cells in this waterproof membrane, thus protecting her brood from fungal attack. Colletes also secrete a substance from their mandibles; it is called “linalool;” the female sprays this fungicide and bacteriocide on her brood cells (O’Toole & Raw 1999).

Diagnostic characteristics: Most Colletes are small to moderate sized bees; (Michener 1994). They range in length from 0.3 to 0.6 inches and have pale bands of hair on their abdomen. Colletes is the only common genus of hairy bees in the family Colletidae, which also includes the relatively hair-free genus Hylaeus (Michener 2000). Colletes carry pollen on scopa (brushes of hair) on the upper part of their hind legs and on their thorax (O’Toole & Raw 1999).

Similar taxa: Colletes are similar to some Andrena and Halictus, but Colletes’ head is more tapered below, giving it a heart-shaped appearance (Michener 1994).

Known conservation concerns:

Interesting fact: One species of fly, Miltogramma punctatum, is a specialist parasite on some Colletes species. It follows a female Colletes back to her nest and hangs out near the nest entrance until she leaves to forage again; the fly then enters the nest, deposits its young in a cell Colletes is provisioning, and leaves. The fly larva eats the pollen and nectar in the cell and the newly hatched Colletes’ larva starves to death (O’Toole & Raw 1999).

Additional resources:

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