As might be surmised by the common name, this species is not native to Washington state or the west coast of North America. Fertilized queens of this species can be commercially purchased.
Tomato plants require “buzz” pollination to maximize their yields. Bumble bees can buzz pollinate, honeybees can’t. For this reason greenhouse growers of tomatoes in British Columbia purchased impatiens queens and raised them in the tomato greenhouses. Some queens escaped and got established in the wild in British Columia. The BC population is expanding and has now been detected in Washington state.
It was just three springs back (2017) that Chris Looney and I documented their presence at Peace Arch International Park, on the Canadian border in Whatcom County, WA. Just this summer (2020) I heard that Bombus impatiens had been detected as far south as King County.
The Common eastern bumble bee currently is restricted to areas west of the mountains with the current (but spreading) population centered near Blaine but now documented as far south as King County. It is not expected to expand into the east side, based on some preliminary “suitable range” analysis done by the excellent team of invasive species entomologists at the Washington state Department of Agriculture. Their modeling suggests impatiens may rapidly spread south through western Washington and into Oregon and California.
Keep your eyes peeled. New county record for your list!
Field ID tips
The Common eastern bumble bee abdomen shows a color pattern of:
The Common eastern bumble bee is the only species of bumble bee with a black end of abdomen in Washington state that has:
T1 = yellow/white
T2 = black