Bombus (Psithyrus) ashtoni (Cresson, 1864)

Zarrillo, Tracy A., Stoner, Kimberly A. & Ascher, John S., 2025, Biodiversity of Bees (Hymenoptera: Apoidea: Anthophila) in Connecticut (USA), Zootaxa 5586 (1), pp. 1-138 : 81

Bombus (Psithyrus) ashtoni (Cresson, 1864)

Ashton’s Cuckoo-Bumble Bee

Notes: This species is listed in Connecticut as “Special Concern” (Connecticut Department of Energy and Environmental Protection 2015b) and is of great conservation interest, as there are few recent records of this social parasite in the Northeastern United States (Dibble et al. 2017; Richardson et al. 2018; Veit et al. 2022[“2021”]) and no recent records in Connecticut (last recorded in 1992). Records for this species in Connecticut are limited, having only nine occurrences in five towns, seven of which were before the year 1925. Williams et al. (2014) stated in a popular identification guide that Bombus ashtoni and Bombus bohemicus “appear to be parts of the same species” so these may comprise a single, widespread, naturally Holarctic species. This synonymy has been accepted or at least noted in subsequent sources, but some authorities prefer to await more rigorous documentation of this synonymy in the technical literature.