Tricolored bumble bee (Bombus ternarius) is hard to miss. Its striking black, yellow, and orange patterning separates are more reminiscent of bumble bees of the western United States than most of our eastern fauna. B. ternarius is widespread, common, and particularly adaptable in suburban and urban areas, though it is also associated with forests and forest clearings. It has likely been increasing in recent years.
Active April through September. Colonies begin producing males and gynes (future queens) by late July and August; one new generation of reproductive individuals per year.
Predominately northern latitudes and mountains. Found in southern part of the northeast in Pennsylvania, New York, and western Massachusetts and Connecticut. Widespread in Vermont, Maine, and southern Canada.
Size > honey bee
Workers: black “T-shaped” spot on thorax; sharp orange banded across abdomen: T1 yellow, T2-T3 orange, T4 yellow, and T5 black
Gynes: like workers, but 2-3x as large
Males: similar size and pattern to females, but with yellow facial hairs
- Red-belted bumble bee (Bombus rufocinctus) can look very similar to B. ternarius, but always has a short face (vs. long malar of B. ternarius) and usually has black (not yellow) following orange bands on the abdomen. Note that B. rufocinctus has highly variable color patterns.
Typically occupies northern hardwood forests, early successional forests, and wetlands. Within those broad regional habitats, commonly occurs on roadsides and in backyards.
Eusocial. Mated gynes (future queens) emerge early in spring and found small colonies in cavities, typically below ground. Colonies produce female workers throughout the summer, then produce new queens and males in the fall.
Highly generalized. Short-tongued species often found on brambles/flowering raspberry (Rubus spp.), azaleas (Rhododendron spp.), milkweed (Asclepias spp.), joe-pye weed (Eutrochium spp.), wood asters (Symphyotrichum spp.), and goldenrods (Solidago spp.).
Bombus [Psithyrus] insularis parasitizes B. ternarius.
Page last updated:
February 22, 2023