Wi BBB: Bombus bimaculatus

photo of Male on obedient plant (<em>Physostegia virginiana</em>) — Male on obedient plant (*Physostegia virginiana*) — Jay Watson

The twospotted bumble bee is found throughout eastern U.S. and southeastern Canada. It is considered one of the most widespread and common bumble bee species in North America (Hatfield et al. 2014, Williams et al. 2014). Wisconsin has many current observation records scattered mostly across the southern half of the state.

The lemon cuckoo bumble bee (B. citrinus) is a nest parasite of the twospotted (Williams et al. 2014). The lemon cuckoo has few Wisconsin records.

The twospotted, 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. 2014). 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: G5 Wisconsin: S4

image showing reference locations of body parts

Identification:

Worker – Face black and vertex yellow. Thorax yellow with a black spot. Abdominal segments T1 yellow, T2 usually yellow with a yellow "W" in the middle surrounded by black, T3-T6 black.
Queen/gyne – Similar to workers, but are larger and appear earlier in the season.
Male – Face yellow or intermixed and vertex yellow. Thorax yellow occasionally with a black spot. Abdomen color pattern is highly varied (see photos), but T1 and center of T2 are typically yellow.
Other distinguishing features – Hair long and uneven.

Similar Wisconsin Species:

Similar bumble bee species in Wisconsin are the common eastern bumble bee (B. impatiens), and the brownbelted bumble bee (B. griseocollis) (Colla et al. 2011, Williams et al. 2014).

Description of Habitat/Range:

Known habitats include woodlands, urban parks, old fields, and gardens (Williams et al. 2014). Nests have been found underground, in cavities, and on the ground surface (Williams et al. 2011).

Nectar Plants

The twospotted is a medium-tongued species (Williams et al. 2014). Nectar plants include Cirsium (thistles), Campanula, Hypericum (St. John's wort), Lonicera (honeysuckles), Melilotus (sweet clovers), Monarda (bee balms), Prunus (plums/cherries), Rhododendron, Rosa, Rubus (blackberry), Solidago (goldenrods), Tilia, Trifolium (clovers), Vaccinium (blueberry), Vicia (vetches) (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:

Known to emerge early. In Wisconsin, observations have been reported mostly between May and September.

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. 2014. Bombus bimaculatus. The IUCN Red List of Threatened Species 2014: e.T44937719A69000240.

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 obedient plant (Physostegia virginiana) — Jay Watson