Rusty Patched Bumble Bee (Bombus affinis), listed as Federally Endangered and State Special Concern, relies on diverse and abundant flowering plant species in proximity to suitable overwintering sites for hibernating queens, which include, but are not limited to, non-compacted and often sandy soils or woodlands. They do not include wetlands. Suitable active season habitat includes but is not limited to prairies, woodlands, marshes/wetlands, agricultural landscapes, and residential parks and gardens. Nectar plants include Aesculus (buckeye), Agastache (hyssops), Asters, Helianthus (sunflowers), Lonicera (honeysuckles), Monarda (bee balms), Physotegia (obedient plant), Prunus (plums/cherries), Solidago (goldenrods), and Vaccinium (blueberry). Queens emerge from hibernation in April and the colony is active through October. In Wisconsin, most recent observations are from the southern half of the state.
The US Fish and Wildlife Service (USFWS) has created a Rusty Patched Bumble Bee High Potential Zone to show where there is a high likelihood for the species to be present. If a project overlaps with this zone steps should be taken to determine if suitable habitat is present for the bee and if necessary, surveys can be conducted. Maps and GIS shapefiles of the zone can be found on the USFWS rusty patched bumble bee page.
