Rufous-backed cellophane bee (Colletes thoracicus)

Colletidae > Colletes > Colletes thoracicus

Rufous-chested cellophane bee (Colletes thoracicus) is the latest of the three spring-flying spring Colletes. This is a “suburban” bee of mid-Atlantic and southern New England states, often occurring in lawns, backyards, and parks. C. thoracicus nests in well-draining soils and is known to associate in massive nesting aggregations that can exceed tens of thousands of nests.


C. thoracicus is active from late-April through June. For the most part, activity does not overlap with activity of similar-sized C. inaequalis. One generation is produced per year.


Mid-atlantic and southern New England, from Virginia north through Massachusetts.


Size ≈ honey bee

Females have a short malar, mostly dark faces, and dark orange thoracic hairs. Fresh individuals have sharp abdominal bands, but worn individuals often lack these bands and have a polished glossy-black abdomen.

Males have a short malar like females, cream to orange thoracic hairs, and dense tufts of hairs on clypeus to form a thick moustache.

Similar species

  • Colletes inaequalis also has a short malar, but is more tan/sand-colored (females especially) and has earlier phenology (~6-8 weeks).
  • Colletes validus is a specialist of sandy, ericaceous heaths and both males and females have an extremely long malar space.
  • Andrena dunningi has slightly earlier phenology, tendency to nest in clayey soils (not usually associated with sand), and wide facial foveae.


Females build nests underground in sandy soils, which could include backyards, lawns, cemeteries, parks, as well as more natural areas. When visible, tumuli are big, conspicuous, and often aggregated.


C. thoracicus forages from a variety of spring-blooming shrubby plants including cherry Prunus, holly Ilex, and tulip tree Liriodendron.

Natural Enemies/Associates

Spring-active Colletes are not parasitized by Epeolus. Blood-winged blister beetles Tricrania sanguinipennis, bee flies Bombyliidae, Leucophora anthomyiid flies, Phorosinella fumosa sarcophagid flies are all known nest parasites. Nests are sometimes raided by ants.


Batra, S.W. 1980. Ecology, Behavior, Pheromones, Parasites, and Management of the Sympatric Vernal Bees Colletes inaequalis, C. thoracicus, and C. validus. J. Kans. Entomol. Soc. 53: 509-538.

Page last updated:
January 17, 2023