Answer:
In general Bombus species do not have many predators because of their vivid warning coloration. Skunks (Mephitis mephitis), Black bears (Ursus americana), and other mammals will consume the comb, adult bees, and their brood. Shrikes (Lanius spp.) and Blue jays (Cyanocitta cristata) are both reported to feed on bumblebees.
There are more parasites of bees rather than predators. In the case of Bombus, other Bombus larvae in the subgenus Psithyrus parasitize in the Bombus nest on their larvae.