The MN Bumble Bee Atlas documented 18 of Minnesota’s 24 species of bumble bees, gathering important data on habitat associations and locations for rarely seen bumble bee species.

Highlights of 2021-2022 bumble bee observations

• The frigid bumble bee, Bombus frigidus, was not documented in Minnesota between 1939 and 2014, but volunteers in Northern MN have been finding them regularly in the last nine years. We do not have enough observations yet to confirm habitat preferences, but they are most often seen near bogs.

• The black tailed bumble bee, Bombus melanopygus, was not confirmed in MN until 2022. This species is more common in the western North America. All sightings to date have been in northern MN.

• There are six species documented historically in MN that we have not found yet in our Atlas efforts. Three of these species have not been seen in MN in recent decades: Bombus variabilis, Bombus ashtoni/bohemicus, and Bombus insularis. These three species are all cuckoo bumble bees. Three other species have been rarely found by other observers within the last five years: Bombus nevadensis, Bombus huntii, and Bombus fraternus. If surveying in far western MN, keep your eyes peeled for huntii. If surveying in southern MN, keep your eyes peeled for fraternus. Bombus nevadensis has been found in both northern and southern MN.

Highlights of 2021-2022 bumble bee floral visitation observations

• Participants documented bumble bees visiting 132 different plant species.

• The top plants across the state and the seasons for abundances of bees were bee balm, Monarda fistulosa (11% of all observations), non-native birds-foot trefoil, Lotus corniculatus (7% of all observations), and fire weed, Chamaenerion angustifolium (6% of all observations).

• The top plants across the state and the season for supporting the largest number of different bumble bee species were joe pye weed, Eutrochium maculatum (13), bee balm Monarda fistulosa (12), fireweed, Chamaenerion angustifolium (11), field thistle, Cirsium discolor (10), and red clover, Trifolium pratense (10).

• Monarda was the most visited flower for affinis, auricomus, bimaculatus, griseocollis, vagans, and our vagans-sandersoni species group.

• Solidago was the most visited flower for frigidus, impatiens, and ternarius.

• Cirsium was the most visited flower for fervidus, pensylvanicus, and terricola.

The figures below show the seasonal pattern of floral use for bumble bees in the southern (below 47 degrees latitude) and northern (above 47 degrees latitude) parts of the state. The observations are grouped over 10-day periods. The size of the dots indicates the number of bees seen and the different colors indicate the numbers of species observed. We want you to visit a wide range of flowers when collecting observations, but when choosing a survey area, you may find more bees and bee diversity if you choose a site with flowers that host lots of bees and lots of different types of bees.