Fernald Cuckoo Bumble Bee (Bombus flavidus), a State Special Concern bumble bee, has been found in boreal forests in Wisconsin. Food plants include thistles (Cirsium species), false goldeneye (Heliomeris species), sweet clover (Melilotus species), typical cinquefoil (Potentilla species), blackberry (Rubus species), ragwort (Senecio species), goldenrod (Solidago species), and clovers (Trifolium species). The Fernald Cuckoo Bumble Bee is a nest parasite of the Redbelted Bumble Bee (B rufocinctus) and the Confusing Bumble Bee (B perplexus) and possibly the Tricolored Bumble Bee (B ternarius) and Sanderson's Bumble Bee (B sandersoni). Adults are active spring to fall.