Members of the family Colletidae are commonly known as plaster bees, cellophane bees, masked bees, and fork-tongued bees. Twenty-four (24) species of colletid bees have been recorded in Pennsylvania [1]. Of these species, only three (Hylaeus leptocephalusHylaeus pictipes, and Hylaeus hyalinatus) are not native to North America (indicated by an asterisk; *). Worldwide, this family has over 2,710 species described [2].

General identifying morphological characters include:

  • A pair of grooves on their face (one below each antenna) 
  • Short tongue length, frequently the tongue is also wider than long, truncated, and/or forked 
  • Small to medium size 
  • Wide range of colors and patterns, but may appear wasp-like, nearly hairless, and have white or yellow markings on the face and other parts of the body

Nesting habitats

Bees in this family nest in burrows they dig in the ground, hollow twigs/stems, or cavities that they find in wood.


All species in this family are solitary, but the females of some species may nest close together. When multiple nests are located in the same area, this is called an aggregation. 

Other behavioral or biological traits

All bees in this family make a cellophane-like lining for waterproofing and protecting their nests. Notably, some species are specialists that only collect pollen from certain plant species, while others are broad generalists that collect pollen from many different types of plants. Members of one group in Pennsylvania, the genus Hylaeus, lack external pollen-collecting structures. Instead, members of this genus carry pollen and nectar internally in their crop (sometimes called the “honey stomach”).

Species list

A checklist of colletid bees recorded in Pennsylvania is presented below. For each species, we list the counties, date ranges, and the most recent years they have been collected or observed in the openly-accessible checklist [see 1].

Genus Colletes — 12 species

Colletes aestivalis Patton, 1879

Colletes americanus Cresson, 1868

Colletes compactus compactus Cresson, 1868

Colletes inaequalis Say, 1837

Colletes validus Cresson, 1868

Colletes latitarsis Robertson, 1891

Colletes nudus Robertson, 1898

Colletes productus Robertson, 1891

Colletes eulophi Robertson, 1891

Colletes simulans armatus Patton, 1879

Colletes thoracicus Smith, 1853

Colletes willistoni Robertson, 1891

Genus Hylaeus — 12 species

Hylaeus (Hylaeus) annulatus (L., 1758)

Hylaeus (Hylaeus) leptocephalus (Morawitz, 1871) *

Hylaeus (Hylaeus) mesillae cressoni (Cockerell, 1907)

Hylaeus (Hylaeus) saniculae (Robertson, 1896)

Hylaeus (Metziella) sparsus (Cresson, 1869)

Hylaeus (Paraprosopis) floridanus (Robertson, 1893)

Hylaeus (Paraprosopis) pictipes Nylander, 1852 *

Hylaeus (Prosopis) affinis (Smith, 1853)

Hylaeus (Prosopis) illinoisensis (Robertson, 1896)

Hylaeus (Prosopis) modestus modestus Say, 1837

Hylaeus (Prosopis) schwarzii (Cockerell, 1896)

Hylaeus (Spatulariella) hyalinatus Smith, 1842 *

Additional information about species in this family is available at:


  1. Kilpatrick SK, Gibbs J, Mikulas MM, Spichiger S-E, Ostiguy N, Biddinger DJ, López-Uribe MM (2020) An updated checklist of the bees (Hymenoptera, Apoidea, Anthophila) of Pennsylvania, United States of America. Journal of Hymenoptera Research 77: 1–86.
  2. Ascher JS, Pickering J (2020) Discover Life bee species guide and world checklist (Hymenoptera: Apoidea: Anthophila).

Photo Credit
USGS Bee Inventory and Monitoring Lab

How to Cite this Webpage
Kilpatrick SK, López-Uribe MM (2020) Colletidae.

Updated 29 June 2020