The Yellow head bumble bee, Bombus flavifrons, is a common bumble bee in Thurston county. It is found around the state, but is most commonly encountered on the west side of Washington.
Field ID Tips
The thorax is cloudy.
T1 and T2 are often bright yellow, contrasting with the black rear.
The majority of individuals I have encountered have black on T3, T4 and T5.
In the San Juan Islands, and I hear from a reliable source, around the Mountain Loop highway, T3 may be replaced with red. An example is shown at the bottom of this page.
The Central bumble bee has the scutum (front of the thorax) yellow, not cloudy. T3 and T4 will be red, with T5 black.
The Sitka bumble bee will have pale reddish hairs on T 4 and T5. These can be a bit subtle.
Male Yellow head bumble bees
are bright yellow and relatively common in the summer time. They are similar to males of Bombus mixtus.
Look for hairy legs with no pollen attached.