Minnesota State Bee: Rusty-Patched Bumble Bee

As part of the campaign to educate the public on pollinators, the most recently adopted symbol of Minnesota—only in 2019—is the Minnesota State Bee: the Rusty-Patched Bumble Bee. A formerly obscure but not uncommon species, Bombus affinis is now famous for its dramatic decline and has become the embodiment of the endangered pollinator. The bees experience wild annual population swings, as only young, mated queens can survive winter. After emerging in the spring, the solitary queen forages for food, defends her nest (usually underground in an old rodent burrow), and tends her young all by herself until enough workers have matured to manage her excessive duties. As pollen sources decline in late fall, the old queen’s dozens of queen daughters burrow down for the winter in woodland litter and suspend their bodies in diapause. The rest of the colony—potentially over a thousand bees—perishes.

So why the sudden, rapid decline? It doesn’t seem to be just any one thing. Habitat loss, for sure; pesticide use, definitely. Then there’s an increase in disease and parasites, possibly introduced through non-native honeybees, and weather plays a huge role: extreme weather, drought or flood, fire, and false springs all are hard on insect populations. But it’s hard to know for sure—for so long, it is simply that they were just another bumble bee; no one really noticed them disappearing until suddenly they were nearly gone.