Members of the family Megachilidae are commonly known as leafcutting bees, mason bees, and resin bees. Eighty-one (81) species of megachilid bees have been recorded in Pennsylvania [1]. Of these species, 14 (Anthidium manicatumAnthidium oblongatum, Chelostoma rapunculi, Coelioxys coturnix, Hoplitis anthocopoides, Lithurgus chrysurusMegachile apicalisMegachile pusillaMegachile rotundata – the alfalfa leafcutting bee, Megachile sculpturalis, Osmia caerulescensOsmia cornifronsOsmia taurus, and Pseudoanthidium nanum) are not native to North America (indicated by an asterisk; *). Worldwide, this family has over 4,110 species described [2].

General identifying morphological characters include:

  • Two submarginal cells on the forewing
  • Long tongue length
  • Small to large size 
  • Wide range of colors and patterns, but may appear wasp-like, nearly hairless, and often have black, brown, or metallic coloration (green, bronze, blue)
  • Females of non-parasitic species have hairs on the underside of their abdomen for carrying pollen 

Nesting habitats

Bees in this family typically nest in tunnels that they either find or construct in wood. They will also use hollow twigs/stems, and other small cavities such as those in pine cones and snail shells. Bits of leaves, flower petals, mud, and/or plant resins are used to seal nests.


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

Megachilidae is one of the most diverse bee families in terms, of behavior and biological traits. Even closely related species or groups of species can be very different! 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. Most bees in this family store food for their young in their own nests, but others are social parasites or cleptoparasites. Parasitic bees invade and lay their eggs in the nest of another bee species. Either the adult parasite or their larva kills the host’s young in the nest. Then, the parasite’s larva eats the food that the host stored. In this way, social parasites and cleptoparasites take advantage of the other species’ efforts to build a nest and collect food.

Species list

A checklist of megachilid 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 Anthidiellum — 1 species

Anthidiellum (Loyolanthidium) notatum notatum (Latreille, 1809)

Genus Anthidium — 2 species

Anthidium (Anthidium) manicatum manicatum (L., 1758) *

Anthidium (Proanthidium) oblongatum oblongatum (Illiger, 1806) *

Genus Chelostoma — 2 species

Chelostoma (Gyrodromella) rapunculi (Lepeletier, 1841) *

Chelostoma (Prochelostoma) philadelphi (Robertson, 1891)

Genus Coelioxys — 12 species

Coelioxys (Allocoelioxys) coturnix Pérez, 1884 *

Coelioxys (Boreocoelioxys) banksi Crawford, 1914

Coelioxys (Boreocoelioxys) moestus Cresson, 1864

Coelioxys (Boreocoelioxys) octodentatus Say, 1824

Coelioxys (Boreocoelioxys) porterae Cockerell, 1900

Coelioxys (Boreocoelioxys) rufitarsis Smith, 1854

Coelioxys (Boreocoelioxys) sayi Robertson, 1897

Coelioxys (Cyrtocoelioxys) modestus Smith, 1854

Coelioxys (Paracoelioxys) funerarius Smith, 1854

Coelioxys (Synocoelioxys) alternatus Say, 1837

Coelioxys (Synocoelioxys) hunteri Crawford, 1914

Coelioxys (Xerocoelioxys) immaculatus Cockerell, 1912

Genus Heriades — 3 species

Heriades (Neotrypetes) carinata Cresson, 1864

Heriades (Neotrypetes) leavitti Crawford, 1913

Heriades (Neotrypetes) variolosa (Cresson, 1872)

Genus Hoplitis — 7 species

Hoplitis (Alcidamea) pilosifrons (Cresson, 1864)

Hoplitis (Alcidamea) producta producta (Cresson, 1864)

Hoplitis (Alcidamea) truncata truncata (Cresson, 1878)

Hoplitis (Alcidamea) albifrons albifrons (Kirby, 1837)

Hoplitis (Alcidamea) spoliata (Provancher, 1888)

Hoplitis (Hoplitis) anthocopoides (Schrenk, 1853) *

Hoplitis (Robertsonella) simplex (Cresson, 1864)

Genus Lithurgus — 1 species

Lithurgus chrysurus Fonscolombe, 1834 *

Genus Megachile — 25 species

Megachile (Callomegachile) sculpturalis Smith, 1853 *

Megachile (Chelostomoides) campanulae (Robertson, 1903)

Megachile (Chelostomoides) exilis Cresson, 1872

Megachile (Eutricharaea) apicalis Spinola, 1808 *

Megachile (Eutricharaea) pusilla Pérez, 1884 *

Megachile (Eutricharaea) rotundata (F., 1787) *

Megachile (Leptorachis) petulans Cresson, 1878

Megachile (Litomegachile) brevis Say, 1837

Megachile (Litomegachile) mendica Cresson, 1878

Megachile (Litomegachile) texana Cresson, 1878

Megachile (Megachile) centuncularis (L., 1758)

Megachile (Megachile) inermis Provancher, 1888

Megachile (Megachile) montivaga Cresson, 1878

Megachile (Megachile) relativa Cresson, 1878

Megachile (Megachilodes) integra Cresson, 1878

Megachile (Sayapis) frugalis frugalis Cresson, 1872

Megachile (Sayapis) inimica sayi Cresson, 1878

Megachile (Sayapis) pugnata pugnata Say, 1837

Megachile (Xanthosarus) addenda Cresson, 1878

Megachile (Xanthosarus) frigida frigida Smith, 1853

Megachile (Xanthosarus) gemula gemula Cresson, 1878

Megachile (Xanthosarus) ingenua Cresson, 1878

Megachile (Xanthosarus) latimanus Say, 1823

Megachile (Xanthosarus) melanophaea melanophaea Smith, 1853

Megachile (Xanthosarus) mucida Cresson, 1878

Genus Osmia — 21 species

Osmia (Diceratosmia) conjuncta Cresson, 1864

Osmia (Helicosmia) caerulescens (L., 1758) *

Osmia (Helicosmia) chalybea Smith, 1853

Osmia (Helicosmia) coloradensis Cresson, 1878

Osmia (Helicosmia) georgica Cresson, 1878

Osmia (Helicosmia) texana Cresson, 1872

Osmia (Melanosmia) albiventris Cresson, 1864

Osmia (Melanosmia) atriventris Cresson, 1864

Osmia (Melanosmia) bucephala Cresson, 1864

Osmia (Melanosmia) collinsiae Robertson, 1905

Osmia (Melanosmia) distincta Cresson, 1864

Osmia (Melanosmia) felti Cockerell, 1911

Osmia (Melanosmia) inspergens Lovell & Cockerell, 1907

Osmia (Melanosmia) proxima Cresson, 1864

Osmia (Melanosmia) pumila Cresson, 1864

Osmia (Melanosmia) sandhouseae Mitchell, 1927

Osmia (Melanosmia) simillima Smith, 1853

Osmia (Melanosmia) virga Sandhouse, 1939

Osmia (Osmia) cornifrons (Radoszkowski, 1887) *

Osmia (Osmia) lignaria lignaria Say, 1837

Osmia (Osmia) taurus Smith, 1873 *

Genus Paranthidium — 1 species

Paranthidium (Proanthidium) jugatorium jugatorium (Say, 1824)

Genus Pseudoanthidium — 1 species

Pseudoanthidium (Pseudoanthidium) nanum (Mocsáry, 1881) *

Genus Stelis — 5 species

Stelis (Dolichostelis) louisae Cockerell, 1911

Stelis (Stelis) coarctatus Crawford, 1916

Stelis (Stelis) foederalis Smith, 1854

Stelis (Stelis) labiata (Provancher, 1888)

Stelis (Stelis) lateralis Cresson, 1864

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) Megachilidae.

Updated 29 June 2020