American bumblebee
Bombus pensylvanicus
Bee
The American bumblebee is a large, long-tongued bumblebee that nests at or near ground level in tall grass, with annual colonies that fly roughly May through September and forage as broad generalists across grasslands, fields, and open habitats. Queens, workers, and males gather nectar and pollen from many plant families, with documented use favoring sunflowers, clovers, goldenrods, and boneset. Once the most commonly recorded bumblebee in the United States, it has declined roughly 89 percent in relative abundance, so a diverse, season-long succession of native bloom directly supports a species now in serious decline.
Conservation
In steep, well-documented decline (roughly an 89 percent drop in relative abundance and major range contraction, especially in the north). Assessed Vulnerable on the IUCN Red List (2015, Hatfield et al.). The U.S. Fish and Wildlife Service issued a positive 90-day finding in September 2021 on a petition to list it under the Endangered Species Act; it is petitioned but not yet federally listed.
Plants in the catalog
Plants this species pollinates · 1
Bumble bees are documented effective Asclepias pollinators (they carry the pollinia); Lanterman Novotny 2023 ranks Asclepias among preferred Bombus plants. Genus-level inference for B. pensylvanicus.
Nectar plants · 17
USDA Forest Service pollinator-of-the-month names boneset (Eupatorium) explicitly as a B. pensylvanicus forage plant.
USDA Forest Service pollinator profile lists goldenrods (Solidago) among documented forage for B. pensylvanicus; a key late-season resource.
Long-tongued bumble bees of the genus Bombus are well suited to the deep tubular corollas.
Lanterman Novotny et al. 2023 document Midwestern Bombus selecting Liatris; genus-level inference for this generalist, not B. pensylvanicus-specific.
Bumblebees work the flat composite heads for nectar and pollen; mapped as a representative native bumblebee visitor of this open-faced aster-family flower.
Linden bloom is a strong nectar draw for bumblebees as well as honey bees; the specific tie to the American bumblebee on this Old-World ornamental is plausible rather than individually documented.
Symphyotrichum asters are a common late-season Bombus nectar source; genus/family-level inference for this generalist, no B. pensylvanicus-specific citation.
Vernonia is documented Bombus forage (Lanterman Novotny et al. 2023); genus-level inference, not a B. pensylvanicus-specific citation.
Vernonia is documented bumblebee forage; the open, nectar-rich clusters are worked heavily by native Bombus through late summer.
Pycnanthemum is a documented Bombus forage genus (Lanterman Novotny et al. 2023); genus-level inference for this generalist bee.
Linden bloom is a strong nectar draw for bumblebees broadly; the same late-bloom starvation caveat applies, and the specific tie to the American bumblebee on this Old-World ornamental is plausible rather than individually documented.
USDA-FS documents B. pensylvanicus on boneset (Eupatorium); Joe-Pye weed is the split genus Eutrochium, so this is a genus-adjacent inference for the generalist, not a Eutrochium-specific record.
Bumblebees are the classic visitors to bluebonnet flowers — heavy enough to trip the keel and reach the nectar and pollen — and are widely credited as a chief pollinator of the spring display.
USDA-FS and Wikipedia: B. pensylvanicus favors clovers (Trifolium); white clover (T. repens) is a documented nectar plant for the species.
Monarda fistulosa is among the most strongly preferred Midwestern Bombus plants (Lanterman Novotny 2023); kept plausible as not B. pensylvanicus-specific.
USDA-FS profile lists columbines (Aquilegia) among plants visited by B. pensylvanicus; a long-tongued bee can reach the spurs.
Pollen plants · 1
USDA Forest Service and Wikipedia note B. pensylvanicus favors sunflowers (Helianthus); common sunflower is a heavy pollen source.
Range
Historically ranged across most of North America from southern Canada through the eastern U.S., Great Plains, and into Mexico, but is now largely absent from the northern parts of its former range.