Posts Tagged ‘vagans’

Half-black bumble bee, Bombus vagans

Friday, July 17th, 2020

The Half-black bumble bee, Bombus vagans, is an east side species in Washington state. While it is considered common across its range, it is a species that I do not encounter on a regular basis when bumbling around the east side of Washington state. When I do find one, it makes it a better field day for sure!

I have detected them in and around Davenport/Reardon, east of Spokane. Based on the limited number of detections shown on the map below, it has never been an easily found species in Washington state.

Having said that, I recently heard and saw video from Chris Loggers up in the Colville area of bushes swarming with B. vagans. Just goes to show: location, location, location!

In a talk by Dr Lincoln Best, he analyzed available Oregan Bumble Bee Atlas data and had few detections of B. vagans relative to many other species. If you see this species please report it to Bumble Bee Watch, iNaturalist or other citizen science documenting sites,

Please reference the Embedded Range Maps page to better interpret
# of observations per ecoregion.

This species is a good example of how much we are learning about bumble bees in Washington state. When the maps above were generated in 2016 they represented the best information easily available for bumbles in Washington state. Fast forward to 2020, where Chris Loggers, in the greater Colville area of the state sent us videos of bushes with well over 100 individual vagans foraging. A nice documented range extension!

Field ID tips

The Half-black bumble bee, Bombus vagans, is a small to medium sized eastside species in Washington. It is a smaller bee relative to the Nevada bumble bee and the Brown-belted bumble bee. The hind end of it’s abdomen is black, and T1 & T2 are yellow. The thorax is predominantly yellow also, usually with a black dot in the alar region. Look for a lump on its face where it might have a nose. I heard this tip from Lincoln Best during his recent (Jan 2021) talk on bumble bees in Oregon.

Similar Species

Similar species include Yellow head bumble bee, Bombus flavifrons and the Common eastern bumble bee, Bombus impatiens.

The Yellow head bumble bee has T1 and T2 yellow (sometimes with some black), but it’s thorax is much cloudier (black hairs mixed in with the yellow hairs). The Half-black bumble bee has the same color yellow on it’s thorax as it has on T1 and T2. The dark spot on the center of the thorax is also more pronounced on the Half-black bumble.

The Common eastern bumble bee is restricted to the west side of the state, so the two species do not overlap. The Common eastern bumble bee has a black T2. The T2 on the Half-black bumble bee is yellow..