Bees of Canada Logo

Megachile fortis Cresson, 1872


Scientific Name: Megachile fortis Cresson, 1872

Common Name: Robust Sunflower Leafcutter Bee


Megachile fortis Cresson, 1872: 262 [♂].

     Lectotype ♂, designated by Cresson (1916: 111). USA, Texas, by Belfrage [ANSP no. 2453].

Megachile emoryi Cockerell, 1904: 7 [♀]. Synonymy by Cockerell (1923: 263).

     Holotype ♀. USA, New Mexico, Pecos, on Kinkale Ranch, 31 August 1903 [USNM no. 9657].

Megachile fortis var. vestali Cockerell, 1913: 530 [♂]. Synonymy by Mitchell (1936: 143).

     Holotype ♂. USA, Nebraska, Halsey, on the sand-hills, 27 August 1911, by A.G. Vestal [USNM no. 29387].


Taxonomic notes: Megachile fortis Cresson, 1872 is the type species for the subgenus Phaenosarus Mitchell, 1934.

Cockerell (1900: 10) indicated that the ♂ of Megachile fortis Cresson, 1872 exhibited different colour variants (i.e., “dichroism”) similar to that exhibited by Anthophora occidentalis and mistakenly indicated that the pale form was described as another species, Megachile comata Cresson, 1872. Though the ♀ was not known at that time, Cockerell (1900: 10) felt that the ♀ of M. texana Cresson, 1878 was M. fortis. Mitchell (1935: 32) indicated that the ♂ lectotype and ♀ paralectotype[s] of M. texana were not correctly associated; the ♂ being associated with the ♀ of M. generosa, and the ♀ being a distinct species that he named M. paratexana Mitchell, 1930 [= M. comata Cresson, 1872]. Cockerell (1923: 263) later indicated that his M. emoryi Cockerell, 1904 represented the true ♀ of M. fortis, though considered his M. fortis var. vestali Cockerell, 1913 a distinct species.

DNA Barcode Index Number (BIN): BOLD:AAJ2888

Biology: This species is a ground nester (Hicks 1926; Cane and Carlson 1984) and builds conspicuous nest tumuli. Neff and Simpson (1991) described the nesting biology and mating behaviour. Aspects of male reproductive behaviour, particularly musculature involved was studied by Fischer (1956). It is considered an oligolege of Helianthus (Mitchell 1936; Bouseman 1982; Neff and Simpson 1990, 1991), despite earlier claims of it being polylectic (Hurd et al. 1980).

Distribution in Canada: Sheffield et al. 2011 [BC, AB, SK, MB], 2014 [AB, SK, MB] - only confirmed record from MB; Gibbs et al. 2023 [MB]

Sheffield et al. (2011) recorded this species from Manitoba to British Columbia, the latter location based on Ivanochko (1979) who examined a specimen from Simon Fraser University that was presumably collected in Summerland, British Columbia. Unfortunately, the specimen was not labelled, so the presence of this species in BC, AB and SK have not been verified. It was not recorded from the BC by Sheffield and Heron (2019).



Cockerell TDA (1900) The New Mexico bees of the genus Megachile and a new Andrena. Annals and Magazine of Natural History, Series 7 6(31): 7-20.

Cockerell TDA (1904) Some bees from San Miguel County, New Mexico. Entomologist 37: 5-9.

Cockerell TDA (1913) Descriptions and records of bees.—LII. Annals and Magazine of Natural History, Series 8 11(66): 530-542.

Cresson ET (1872) Hymenoptera Texana. Transactions of the American Entomological Society 4: 153-292.

Mitchell TB (1935) A revision of the genus Megachile in the Nearctic region. Part II. Morphology of the male sternites and genital armature and the taxonomy of the subgenera Litomegachile, Neomegachile and Cressoniella. Transactions of the American Entomological Society 61(1): 1-44.

Mitchell TB (1936) A revision of the genus Megachile in the Nearctic region. Part IV. Taxonomy of the subgenera Xanthosarus, Phaenosarus, Megachiloides and Derotropis (Hymenoptera: Megachilidae). Transactions of the American Entomological Society 62(2): 117-166.

Neff JL Simpson BB (1991) Nest biology and mating behavior of Megachile fortis in Central Texas (Hymenoptera: Megachilidae). Journal of the Kansas Entomological Society 64: 324-336.

Sheffield CS, Frier SD, Dumesh D (2014) The bees (Hymenoptera: Apoidea, Apiformes) of the Prairies Ecozone, with comparisons to other grasslands of Canada. In: Giberson DJ, Cárcamo HA (Eds) Arthropods of Canadian Grasslands (Volume 4): Biodiversity and Systematics Part 2. 4. Biological Survey of Canada, Ottawa, 479 pp. [ISBN 978-0-9689321-7-9].

Gibbs J, Hanuschuk E, Miller R, Dubois M, Martini M, Robinson S, Nakagawa P, Sheffield CS, Onuferko T (2023) A checklist of the bees (Hymenoptera: Apoidea) of Manitoba, Canada. The Canadian Entomologist 155: E3.

Sheffield CS, Heron JM (2019) The bees of British Columbia (Hymenoptera: Apoidea, Apiformes). Journal of the Entomological Society of British Columbia 115: 44-85.

Cresson ET (1916) The Cresson types of Hymenoptera. Memoirs of the American Entomological Society 1: 1-141.

Sheffield CS, Ratti C, Packer L, Griswold T (2011) Leafcutter and mason bees of the genus Megachile Latreille (Hymenoptera: Megachilidae) in Canada and Alaska. Canadian Journal of Arthropod Identification 18: 1-107.

Cockerell TDA (1923) Descriptions and records of bees.—XCVII. Annals and Magazine of Natural History, Series 9 11(62): 263-269.

Fischer RL (1956) The muscular mechanism of the male metasoma and genitalia of Megachile fortis Cresson (Hymenoptera: Megachilidae). The Canadian Entomologist 88(12): 657-673.

Sociality: Solitary
Nesting: Ground
Pollen Specialization: Broad Oligolecty
Wintering Stage: Mature Larva

Crop Preference: Not Available
Non Crop Preference: Not Available

Distribution: Manitoba
Ecozone: Prairie

Distribution Map