What do you use for bumblebees? -Alan, MD
Bumblebees are rarely a real problem, and serve far more benefit to a landscape or an environment than a hazard. With a little luck and some education of the customer perhaps they can understand that not all stinging insects need to be killed. Of course, there are always situations that call for their elimination, and if they are nesting within a structure then this may be one of those times. If there are excessive numbers of nests on a property and people may be interacting with the bees too frequently, then this could call for elimination of the nests. But, foraging bumblebees really don’t care a hoot about what’s going on around them as long as no one directly antagonizes the bee. I have often moved through vegetation where large numbers of bumblebees were working the flowers (moving carefully and slowly I admit) and have never had a bee act aggressively toward me. Preserving them is a good thing if possible.
But, get too close to their colony and they too, as social bees, may defend things with a sting. Bumblebees are opportunistic in their selection of places to have their colony. Their society is similar to that of honeybees, but with much smaller colonies. Any small void is satisfactory, including old bird houses, voids in walls, holes in the ground, old logs, etc. The control is most effective by searching for the nest itself and treating directly into it. A contact insecticide dust would be most effective, such as DeltaDust, Tempo Dust, Drione Dust, or possibly Apicide dust. Treating the nest opening directly minimizes any effect on other organisms outside the nest, and is the best way to contact the bees as them come and go. This really is your best and only option, because trying to control the bees while they are foraging is not effective, and there are no repellents to discourage them from being in an area if pollen is available.
Managing other food resources does need to be examined though, as the adult bees are drawn to sweet liquids, just as honeybees and yellowjackets are. If you have outside eating areas, such as picnic tables, where spills of sodas or syrups will be, these will draw bumblebees and bring them close to people. Sanitation and cleaning of such areas helps prevent the presence of the bees. If you have large populations of aphids or other honeydew-producing insects on trees or shrubs, this sweet material also may draw bumblebees. Sometimes scale insect problems on ornamental trees can produce copious amounts of honeydew on sidewalks and patios below the trees. Control the plant pests to eliminate the source and wash the surfaces to remove the honeydew and this will help too.
Mr. Pest Control