Bombus affinis: the Rusty Patched Bumble Bee

Bombus affinis, commonly know as the Rusty Patched Bumble Bee, is a social species of bumble bee native to eastern North America which can be easily identified by a small rust-colored patch located on the middle of their second abdomen. They act as native pollinators to a variety of wildflowers and crops including cranberries, plum, apple, alfalfa, and onion seed.

Rusty patched bumble bee populations were once widely distributed, but has declined from an estimated 87% of its historic range in recent years. The exact cause of  this decline remains unknown, but hypothesized causes supported by studies suggest exposure to pesticides, exposure to disease, habitat loss, invasive species, and effects of climate change are significant contributors. B. affinis was listed as critically endangered by the IUCN Red List in 2015 and federally endangered in the United States in 2017. It is one of about 21 species of bumble bees in the eastern United States.