Moved from Bumble Bees.

This species is the earliest emerging bumblebee in the Seattle Area.Queens usually can be seen in February, or when the pussy willows flower. It usually completes it`s life cycle in May--often before the first workers of other species like B. californicus emerge.In the last several years, I`ve found a couple of second generation nests, in which new queens instead of going into hibernation, started another colony, although the population much smaller due to declining amounts of their favorite food sources, and expanding populations of parasites, like wax moths.
If you accidentally disturb a colony in the wild, you`ll know if its a b. melanopygus by the ferocity and distance that you will be chased by the defenders! Unlike most other bumblebees that I am familiar with, the defenders do not give up just outside the nest entrance--they will follow and attack you upwards of 50 to 100 feet or so.

that species is unknown in Oregon