Bumble Bees

Genus: Bombas
Pest type: Stinging insect
Beneficial role: Pollinator

Should I Worry About Bumble Bees?

Adult bumble bees feed on flower nectar and pollen. Because of this, they don’t present a problem around human food or garbage because they do not scavenge the way yellowjackets do. Bumble bees are a small-to-moderate sting risk to humans when foraging. Stings can occur when a bee is in the wrong place or a bee is stepped on with bare feet. They are docile when alone, and do not sting unless they perceive danger to themselves or the hive.  A severe sting event is most likely to occur when the colony is disturbed by human or animal activity including the use of a mower or weed trimmer. Unlike honey bees, bumble bees can sting repeatedly like wasps.  If someone in your household has a known allergy to wasp or bee venom, be sure to have an emergency plan. 

Reducing risk of stings

Avoid swatting or squashing bumble bees. Gently blow off, or brush off a bumble bee that has settled on you. Avoid walking barefoot in lawns with clover or other flowering weeds where bees are foraging. Scoop live bees and wasps out of swimming pools and place them away from busy areas. If you are concerned about a wasp or bee nest, consult a professional pest management company or beekeeper.

Bumble Bees are important pollinators that face an uncertain future as their numbers dwindle. As with all insects and arachnids, we advocate understanding the biology of a species and the use of integrated pest management to reduce risk. Scouting—the act of purposely looking for pest nests and pest activity—can reduce problems later in the year when the colony is well-established. 

 

About Bumble Bees

What Do Bumble Bees Look Like?

Depending on the species, bumble bees can be up to one inch long (26 mm) but there is variation within a colony as well. Their thick bodies are often black with yellow or occasionally orange markings, and densely covered with hair. There are about fifty species in the US with similar traits.

Bumble Bee Colonies

Bumble bees build colonies of 50-400 in the ground—abandoned animal burrows, soft soil or organic matter like hay bales—or occasionally in structural cavities close to the ground. Like wasps, their queens are the only ones to survive over the winter, emerging in the spring to start a new colony.

Why Do I Have Bumble Bees in My Yard?

To feed the brood, adult bees forage for pollen and nectar flowers of fruit trees and shrubs, vegetables and ornamental plants. It is common to see bees on flowers on a sunny day. Having bumble bees around the yard and garden is a good sign of a healthy environment.
 

How Do I Manage Bumble Bees in the Landscape?

Because bumble bee nests are hard to find, it makes sense to scout for stinging insect activity throughout the season. If you discover an active bumble bee nest, consider how much risk it presents. Is it in an area with constant human or pet traffic? Or can it be avoided?  If you find a large nest block access to it as much as you can. Bumble bees, in general, are becoming more rare in North America, so tolerating their presence helps their survival. If the risk of stings can’t be ignored, call your local cooperative extension for a list of experienced pest control experts.

Management Timeline for bumble bee problems:

Early spring through summer:
If bumble bees have been a problem in the past, monitor buildings and grounds for bumble bee nest activity on warm sunny days; try to do this every other week. Pay close attention to the foundation of the building, stumps, wooden fence posts,  compost piles, and areas of heavy vegetation. Bumble bees are usually ground-nesters. Watch for foraging workers and where their travels take them. This helps you discover nests or hive locations. 

Late summer through fall:
Continue to monitor buildings and grounds. If you find a bumble bee nest you can keep isolated from people and pets, leave them be. Consult an expert if you find an active colony that poses a stinging risk.  Note where you find nests so you can make the sites unavailable for the following season, as bumble bee queens may return to the same area.

Winter:
Plan a prevention strategy for the following season. Find and fill areas along the foundation or in soft soil where rotted wood or old animal burrows can accommodate ground nests. Rotate compost piles before or in early spring. Always have an action plan in place to care for people and animals who have been stung.