To eliminate bumble bees, locate the bees' nest and treat it with soapy water or insecticide dust. Aerosol-type insecticide spray is used to treat exposed nests.
To eliminate a nest of bumble bees living underground, observe the bees to locate their nest, and pour a mixture of dish soap and water into the nest entrance. If the bees remain active after treating the nest with soapy water, apply an insecticide dust, such as carbaryl or chlorpyrifos, to the nest according to the directions on the product packaging.
If the bees are living inside a wall cavity, drill a hole in the exterior wall that is covering the nest, and apply insecticide dust to the nest. To apply the insecticide, use a bottle with a tapered tip or spout, and place the spout of the bottle into the nest entrance. Squeeze the bottle to puff the insecticide dust into the wall cavity. After the bee activity on the property ceases, seal the nest entrance and drilled holes near the nest with caulk.
If an underground nest is exposed by digging, wear protective clothing and spray the exposed nest with an insecticide spray that is labeled for outdoor use. Do not spray flowers with insecticide, as this may harm beneficial insects.