On Tulipa tarda
Foraging on Baptisia bracteata in a seed production plot
I didn't see any bumble bees at the big gooseberry all day until the chainsaw and other machinery taking down a dead Ash next door was off for a while. Does consistent loud "buzzing" keep queens away. If this is a brown-belted bumble bee the brown belt is the smallest I've seen.
Nectaring on white clover
Smaller, more obvious brown on abdomen than the other bumblebees (https://www.inaturalist.org/observations/215540615)
At Lamprocapnos spectabilis