Two-form bumblebee (Bombus bifarius)

A bumblebee with his head stuffed into a yellow flower

Two-form bumblebee (Bombus bifarius)

The two-form bumblebee thankfully are of least concern on the International Union for Conservation of Nature (IUCN) list, which includes the conservation status of all biological species. Two-form bumblebees are specifically found in the mountainous areas of western North America. They feed on a wide range of wildflowers found in GTNP such as blue bells (Mertensia), green gentian (Frasera speciosa), and cinquefoils (Potentilla). Queens emerge in early spring, search for a place to start a colony- typically in the ground- where begin laying eggs and gathering resources.

This bumblebee gets its name from the two dominant polymorphisms, meaning the two dominant phenotypes you may see with this species. On a bee’s abdomen, the segments are broken down into what are called metasomal tergite. In worker bumblebees, they have 6 segments, which are referred to as T1-6. In the two-form bumblebee, T2-3 can be either orangey-red or black, depending on the geographic location. 

A helpful PDF guide on bumblebees can be found here: https://www.fs.fed.us/wildflowers/pollinators/documents/BumbleBeeGuideWestern2012.pdf

Written by Anna Cressman
PC: Anna Cressman