Wi BBB: Bombus sandersoni

photo of Male on dandelion (<em>Taraxacum officinale</em>) — Male on dandelion (*Taraxacum officinale*) — Jerry McCormick

The Sanderson's bumble bee is known from the eastern U.S. and appears to be stable there (Hatfield et al. 2015). Wisconsin is on the edge of its range and is not common, but has several recent observations from the northern part of the state in Oconto and Oneida Counties.

The Sanderson's bumble bee, like other bumble bees, live in colonies composed of a single queen and female workers. Colonies start to produce new queens and males in the mid- to late summer. Only new, mated queens overwinter, emerging from diapause (a form of hibernation) in the spring. New queens are responsible for finding a new nest site, laying eggs, and for all of the foraging and care of the colony until the first workers emerge (Hatfield et al. 2015). Once the first workers emerge, the queen remains in the colony laying eggs. Bumble bees need areas that provide nectar and pollen from flowers throughout the duration of the colony life cycle, and suitable sites for nesting and for overwintering queens.

Status-Global/State:

Global: G4G5 Wisconsin: S1S3

image showing reference locations of body parts

Identification:

Worker – Face and vertex black or intermixed with yellow. Thorax mostly yellow with black spot or band between the wingpads and sides all yellow. Abdominal segments T1-2 yellow, and T3-T6 black. Some morphs have yellow hairs on T5.
Queen/gyne – Face and vertex may be yellow, black or intermixed. Thorax mostly yellow with black spot or band between the wingpads and sides all yellow. Abdominal segments T1-2 yellow, and T3-T6 black. Some morphs have white or yellow hairs on T5.
Male – Face intermixed and vertex yellow. Thorax may have a black spot or band. Abdominal segments T1-2 yellow and T3-T7 black. Some morphs have intermixed hair or fringes on T3, T4 or T5.
Other distinguishing features – Small bee with a round face and short and even hair. Difficult to distinguish females from half-black bumble bee (B. vagans) and confusing bumble bee (B. perplexus); and males from half-black bumble bee (B. vagans) and redbelted bumble bee (B. rufocinctus).

Similar Wisconsin Species:

This species is difficult to identify. Similar bumble bee species in Wisconsin are twospotted bumble bee (B. bimaculatus), common eastern bumble bee (B. impatiens), frigid bumble bee (B. frigidus), confusing bumble bee (B. perplexus), and half-black bumble bee (B. vagans) (Colla et al. 2011, Williams et al. 2014).

Description of Habitat/Range:

Known habitats include wooded areas (Williams et al. 2014). Nests have been found mostly underground (Colla et al. 2011, Williams et al. 2014).

Nectar Plants

The Sanderson's bumble bee is a short-tongued species (Williams et al. 2014). Nectar plants include Cimicifuga, Epilobium, Kalmia, Lonicera (honeysuckles), Lyonia, Malus (apples), Melilotus (sweet clover), Monarda (bee balms), Penstemon (beard tongues), Rubus (blackberry), and Vaccinium (blueberry) (Williams et al. 2014, Colla et al. 2011).

Click on the legend symbols for each type of bumble bee to add or remove them from the graph.
Data from verified B3 observations [updated 2/28/2024].

Flight Season:

In Wisconsin, the few observation records are mostly from August. Range-wide, queens start emerging in May and enter diapause in July (Colla et al. 2011).

Literature Cited:

Colla, S., Richardson, L. and Williams, P. (2011) Bumble Bees of the Eastern United States. A product of the USDA Forest Service and the Pollinator Partnership with funding from the National Fish and Wildlife Foundation.

Hatfield, R., Jepsen, S., Thorp, R., Richardson, L. & Colla, S. 2015. Bombus sandersoni. The IUCN Red List of Threatened Species 2015: e.T44937931A46440296.

Williams, P.H., Thorp, R.W., Richardson, L.L. and Colla, S.R. (2014) The Bumble bees of North America: An Identification guide. Princeton University Press, Princeton.

Male on dandelion (Taraxacum officinale) — Jerry McCormick