Bugs Around Your House
3. Bumble Bees
(Scientific name: Bombus spp;
Family: Apidae; Order: Hymenoptera)
Description With a total of about 239 species worldwide, there are probably 15-18 different species of bumble bees in Michigan and the surrounding states. The most common one is probably B. impatiens, depicted below in the photos. Queens are about 1 inch long, workers from 1/4 to 1/2", both hairy looking. Bumble bees seldom sting, unless provoked near their nest or steped upon with no shoes. However, when they do sting, they can inflict pain mulitple times, unlike the honey bee.  

Above: A bumble bee queen foraging on a flower near Boston, MA. Notice the pollen on her pollen baskets on her hind legs. Right: A peek nside a bumble bee nest, the larger bee in the center is the queen. Workers of different sizes are seen incubating brood in brood cells. The open cells are honey pots. Photogrphed indoor at a commercial bumble bee supplier. Photos by Zachary Huang

Behavior and Biology Bumble bees have an annual cycle, similar to paperwasps and yellowjackets. The queens overwinter inside leaf litter or loose soil and tries to find new nests around April and May in Michigan. They nest in mouse nests or abandoned ground hog holes, occasionally in bird houses or wall cavities. The queen will forage for nectar and pollen and take care of her first batch of 'brood' (a term used for larvae and pupae of social insects). Once the workers (which are sterile as in honey bees) emerge, she retires from foraging task and stay home as a full time mother (laying eggs and incubating brood). Workers will forage for pollen and nectar and bring into the colony. A nest around September may contain 300-700 workers. New queens are produced in the fall and will mate and find shelters to overwinter. Males, workers and the old queen will die during winter and only mated queens survive.

Important Pollinators Bumble bees can be better pollinators than honey bees in many aspects. First, they fly at cooler temperatures and work at earlier and later hours than honey bees. Two, they have a special mode of pollination behavior called "buzz pollination" in that they vibrate their body in high frequency to shake the pollen loose from flowers. This behavior is more efficient and almost required for pollination in some crops such as eggplants, tomatoes (both solanaceous plants) and blueberries. Thirdly, they seem much better than honeybees in getting home when inside enclosures. The buzz pollination and homing ability makes them the ideal pollinator for greenhouse plants (mainly cucumbers and tomatoes). They also work on flowers much faster than honeybees. In a three-year study (1992-94), Javorek, MacKenzie and Vander Kloet reported that a bumble bee pollinated twice as many lowbush blueberry flowers as a honey bee in the same amount of time, they also pollinated in 80 percent of their floral visits while honeybees only about 25 percent, they also deposited 34 tetrads (four pollen grains are fused together in blueberries) per visit while honeybees only 13. This makes a bumble bee about 24 times more efficient than a honey bee, on a worker for worker basis, for blueberry pollination.

Control and Prevention Because bumble bees are important native pollinators, it is not recommended to kill them. To prevent them from nesting near your property, fill in all animal borrows and holes in soil and seal holes and cracks on sidings, screen all vents. If they nest near your house and someone is allergic to insect stings, killing is the only option because it is not practice to relocate them. If they are nested under ground or inside a wall cavity, wait till after dark for all workers to return home, then pump dusts (Sevin), inject sprays (general bugspray or resmethrin), or pour water containing insecticides (Baygon, containing propoxur) into the hole. Cover the whole with soil after done to prevent unpoisoned bees from escaping the next day. If you are allergic to insect stings, have someone help you, or call a pest control firm listed in your yellow pages.

Disclaimer: This fact sheet is for information only. Mention of products does not indicate endorsement. Prepared by Zachary Huang, Department of Entomology, Michigan State University, East Lansing, MI 48824, USA. email: bees@msu.edu.

url: http://cyberbee.msu.edu/column/stinging/bumble.pdf