Bumblebee

Bumblebee (Bombus spp.)

Description: The Bumblebee is a widely distributed social insect know for its ability to collect nectar from flowers and pollinate plants. Bumblebees are large yellow and black flying insects with a distinct buzz. There is variation in coloration among bumblebees and some species have bands of red, yellow and black. They have stocky bodies that are covered with many hairs to which pollen adheres.

Bumblebees have four wings, the two rear wings are small and usually attached to the fore wings by a row of hooks called hamuli. The wings move rapidly, at 130-240 beats per second.

Beneficial insects. The bumblebee's commercial value is as a pollinator of crops. See photo of a bumblebee collecting nectar.

Range / Habitat:
There are over 250 known species, existing primarily in the Northern Hemisphere. Hedgerows near orchards provide food and shelter for pollinators like bumblebees.

Behavior:

Bumblebees are social insects that live in colonies. The queen bee, drones and worker bees all have specific tasks to help support the colony. The queen bee lays hundreds of eggs. The male drones' main function is to be ready to fertilize a receptive queen.Worker bees do all the different tasks needed to operate and maintain the hive.

The average mass of pollen and nectar carried by bumblebees returning to the nest is around 25% of their body weight. However some bumblebees fly back carrying as much as 75% or more of their body weight!

Foraging bumblebees tend to avoid flowers recently visited by other bumblebees, although they will visit the same patch of flowers. Bumblebees will scent mark the flowers - leaving behind a message to others that the nectar is gone. The scent is secreted from a gland in the bumblebee's tarsus. Scent marking reduces the time spent probing flowers without nectar.

Some bumblebees cheat by collecting nectar from a plant without entering and pollinating the flower. This is known as nectar robbing. "The bee will crawl on the outside of the flower close to where she thinks the nectar is located, and then with her tongue sheath and mandibles she bites and pokes a hole in the flower. Then she inserts her tongue sheath, extends her tongue and mops and sucks up the nectar. Later other bumblebees may use the hole." (source: bumblebee.org)

Do Bumblebees sting?

Bumblebee workers and the queens can sting, and their stinger is smooth - not barbed like that of the honeybee - so they can sting more than once. Male bumblebees cannot sting as they do not have a sting.

A honey bee can sting once, since the sting has barbs and it will rip off and stay in the victim's skin.

Reproduction:

The queen bee lays all of the eggs in a colony. The queen fertilizes each egg as it is being laid using stored sperm from the spermatheca. The queen occasionally will not fertilize an egg. These non-fertilized eggs, having only half as many genes as the queen or the workers, develop into male drones. Pollen stimulates the ovaries to produce eggs, which the queen lays in batches of 4 -16 on the ball of pollen which is then covered with wax.

The queen keeps the eggs warm at about 30 ^oC. She has a bare patch on the abdomen so heat from the queen's body can pass directly to the clump of wax-covered eggs. A Bombus terrestris queen may have to visit as many as 6,000 flowers per day in order to get enough nectar to maintain the heat needed to brood her eggs!

Did you know?

• Bumblebees harvest nectar and pollen from flowering plants.
• They live in smaller groups than honey bees and do not tend to swarm.
• Bumblebees hibernate underground.
• They scent mark flowers they have visited.
• Bumblebees will not die if they use their sting, whereas honey bees will.

Bumblebee collecting nectar.      photo by Tim Knight

More information:
BeeSpotter - BeeSpotter is a citizen-scientists partnership designed to educate the public about pollinators.
Bumblebee Anatomy (pdf)
Bumblebee.org - lots of information about Bumblebees
Grant to help restore bumblebee habitat near farms
North American bumblebees
Bee and Wasp Stings
Washington State Beekeepers Association