These mate during flight and fertilized females move to overwintering sites. Remaining males and workers in the colony die with frost or the first hard freeze. Nests can be detected by the presence of many males flying about the entrance. Easily irritated, workers will aggressively pursue an intruder attempting to escape. Bumble bees are extremely important pollinators of certain kinds of clover such as red clover due to their long tongues.
Favored flowers are sunflowers, thistles, nettles, roses, partridge peas and certain clovers.
They frequently alight on sweaty hands and inflict a sting which is somewhat painful lasting for a half hour or more. These bees are common at flowers, gathering pollen and nectar to feed their young. Nests occur in cavities in weeds or shrubs, or in the ground. Andrenid bees, as Halictid bees, are solitary, short-tongued and nest in burrows in the ground, sometimes in large numbers, nesting close together where vegetation is sparse. They are gregarious and nest in groups.