Bumble bees of the genus Bombus are robust and densely covered with black and yellow hairs (setae), the pattern of colors varying with species. They range in size from about 0.5 to 1.0 inch long.
Bumble bees are social and nest in existing cavities, usually on or in the ground. They often use abandoned mouse nests, bird nests or anything containing cotton or other soft materials. Only fertilized queens survive the winter.
Bumble bees seldom enter structures and do not behave very aggressively except in defense of their nest. Normally they are a nuisance only if they have built a nest close to human activity.