About Bombus sonorus Say, 1837
Female Bombus sonorus are identified by yellow thoracic hairs covering the pronotum, the anterior portion of the scutum, and the scutellum, which forms a black band between the bases of the wings. The first three abdominal segments, T1 to T3, are entirely yellow in females. Males share this general appearance, but have yellow coloration on T1 through T4 instead. The yellow shade of this species is a deep golden color. This species can be mistaken for the yellow form of Bombus crotchii, and also for Bombus nevadensis. Recorded pollen host plants for Bombus sonorus include flowers of the genera Gossypium, Viguiera, Helianthus, Linaria, Chrysothamnus, and Kallstroemia. Bumblebees of this species typically nest underground, and most often use old pocket gopher burrows for nesting. This species ranges from California to central Texas in the United States, and extends south into southern Mexico. It is most closely related to Bombus pensylvanicus. The two species share overlapping ranges in the western half of Texas, parts of New Mexico, and parts of Mexico. Bombus sonorus is a member of the subgenus Thoracobombus. Bombus pensylvanicus sensu lato, a group that includes Bombus sonorus, is currently under review for federal protection under the United States Endangered Species Act, and is classified as Vulnerable on the IUCN Red List.
