Numbers and Types
There are more than 20,000 species of bees around the world and more than 200 of them are bumble bees. Within each of these species, bumble bees come in only three types. The "queen" is responsible for reproduction and laying eggs. "Worker" bees -- which are female -- perform several duties, including food collection in the form of nectar and pollen, as well as taking care of young, and basic cleaning duties around the hive. "Drone" bees -- which are male -- mate with the queen, ensuring fertilization. That is their sole responsibility.
Stingers
There are common misconceptions about stingers and bees. One is that all bees sting -- or at least have the ability to sting -- which isn't true. Bumble bee drones do not have stingers and therefore cannot sting. Although other bumble bee types do sting, they usually sting out of defensive of the hive, so people are advised to avoid bumble bee nests. Another common misconception is that all bees die after stinging; however, this only applies to honey bees. A bumble bee does not lose its stinger after stinging and therefore is fine.
Wings and Scents
Bumble bees have four wings, which move up to 240 beats per second. The rear ones attach to the front ones by hooks known as "hamuli." When a bumble bee visits a flower, it is able to avoid flowers already exhausted by other bumble bees through scent detection. Every time a bumble bee visits a flower, it marks the flower through the use of a scent-gland within the tarsus.
Lifecycle
The bumble bee's life cycle generally begins around spring when the queen first begins to mate and lay eggs. The nests initially have pollen storage reserves and eggs -- laid six at a time -- which are sealed in by wax. The queen eventually creates a cocoon for the small grubs from which the eggs emerge within a few days.