Bumble Bee

The common name of bumble bee possibly comes from its rather large, clumsy appearance and/or the buzzing sound it makes as they fly. In the urban setting, bumble bees usually do not nest in structures but are of concern because of their sting. There are about 51 species in the United States and Canada, and as a group they are found throughout the United States.

Recognition

Adult worker body length about 1/4-1 inch, queens about 3/4-1 inch long; robust in form. Color black with yellow markings; with between base or compound eye and base of mandible. Hind tibia with apical spurs. Front wing and second submarginal cell more or less rectangular, about as long as first submarginal cell. Hind wing lacks a jugal lobe. Stinger relatively smooth, with small barbs.

In addition, Bombus with hind tibia modified into pollen basket whereas, Psithyreus lacks pollen basket, hind tibia slender.

Habits

Depending on the Bombus species, the over-wintering queen will select and appropriate a nesting site the following spring. The queen of some Bombus species locate a dark cavity at least 3/4 inch high by 1-1/8 inch wide containing fine plant fiber; such a nest usually is underground and often an abandoned mouse nest. Queens of other Bombus species select a dense clump of grass on the surface for a nest, adding grass on top. The queens of Psithyreus species all are parasitic on the Bombus nest, so they bide their time until the Bombus nests are moderate in size and can therefore support them. They then enter the nest, kill the Bombus queen, and take over the nest using the Bombus workers to care for the queen's young. Bombus queens of later emerging Bombus species also sometimes parasitize the nest of earlier emerging Bombus species.

Bumble bees foraging for nectar fly at 7-12 m.p.h. and spend only two to four minutes inside the nest between trips. Probably they will travel at least three miles if necessary for nectar. They are orientated by the sky's polarized light via their three ocelli, so they can travel before and after light when objects and landmarks are not visible. They use their thermoregulation procedure to warm up flight muscles before the sun rises and to also forage when temperatures are below 50 degrees; whereas most bees stop foraging at 61 degrees. Each worker forages independently, and bumble bees never exchange food. Old cocoons are used to store both pollen and nectar. Only enough food for a few days is stored at any given time, which helps discourage nest raids by skunks, foxes, etc.