Bumble Bees of Montana
Bombus (Pyrobombus) impatiens Cresson, 1863 Common Eastern Bumble Bee
Bombus impatiens Cresson is a common eastern North American species whose native range extends only as far west as Nebraska and Minnesota (Williams et al. 2014). It has been commercially reared for greenhouse pollination services and research since the 1980s (Koppert Biological 2015). Concerns have been raised about the transport of this species to the western U.S., and the possible consequences for native bees if feral B. impatiens colonies became established outside of their native range (Xerces Society et al. 2013). Hives contain queen excluders in order to prevent the escape of new queens and the establishment of feral colonies (Planet Natural 2016). Still, the use of these colonies is of some concern, with potential consequences including the development of feral colonies by escaped queens, pathogen spillover (McMahon et al. 2015), and competition with native pollinators (Potts et al. 2010, Morales et al. 2013, Graystock et al. 2016).
One verified specimen of B. impatiens was collected in Ravalli County in June of 1980 from a locality on the western side of the continental divide, well beyond the known range of B. impatiens and before the widespread use of B. impatiens as a commercial pollinator (Snow Entomological Museum Collection, University of Kansas, SEMC). Six other specimens originally included in the database are from a research project using commercially reared B. impatiens in a comparison between organic and conventional wheat fields in one location in Chouteau County. These six records were added to the database as documentation in case feral colonies of this species are detected in that region in the future.
Recorded Montana Distribution
Diagnosis
Bombus impatiens has a cheek that ranges from approximately as long as it is wide to just shorter-than-wide. Only abdominal T1 is yellow, T2-T6 are all black.
Similar Species
This species is most easily confused with B. griseocollis in Montana, but B. griseocollis has a shorter-than-wide cheek and T2 is yellow or brown, at least in the middle.