There are a number of bumble bee species native to the U.S.; we use primarily Bombus impatiens at NCRPIS. Bumble bees are known to pollinate many plants, however they excel at pollination of plants with trumpet-shaped flowers due to their long tongues. At NCRPIS, bumble bees are used primarily for pollination of Baptisia sp. and Calendula sp. in approximately 12 cages annually.
Bumble bees are social insects whose colonies only survive one year. New queens mate late in the summer and hibernate individually over the winter; the following spring these queens each establish a colony. A bumble bee colony consists of a queen, numerous workers (female), and drones (male). Bumble bee colonies pollinate throughout the summer and die off in the fall. They forage at 55 to 90 F (13 to 33 C) in all types of weather. Unlike other bees, bumble bees will continue to work in cool rainy conditions. These bees are mildly aggressive when they feel threatened. Rearing is possible, but difficult. Colonies are available through several commercial sources.
NCRPIS purchases "research colonies" consisting of a queen and 30 to 40 workers (queen-right colony). The furnished domicile consists of a cardboard box containing a plastic chamber which rests on top of a plastic feeding bag. The chamber houses the nesting area; bees are provided upholster's cotton within which they build the brood nest. A cotton wick bridges the area between the nest and the feeding bag below. The feeding bag contains high fructose corn syrup. Initially bees can only exit the box once a sliding tab has been opened and lightweight mesh fabric is removed. Once a hive has been opened, bees can be allowed to enter/exit the box as appropriate by setting the slides as recommended by the supplier.
If the queen-right colony is found to be too aggressive in working tender flowers, the use of a "drone-only colony" is recommended. Drones (male bees) tend to have a more "mellow" disposition; they cannot sting.
Bumble bee hives are placed entirely within the cage regardless of cage size. They are placed within a protective frame to reduce weather damage to the cardboard box. When bumble bees are no longer needed in a cage, the slide is set to "entrance only" and the hive is collected between the hours of 9 PM to 7 AM.
Bumble bees are allowed to forage freely when not in cages. They are not stored in any way over the winter; individual colonies are allowed to die off naturally.