Bumblebees do sting, but they very rarely do so.
To wit, one British specialist who has spent years studying the bumblebee species notes to their astonishment that they have never once been stung.(1) Even though the queen and worker bumblebees have the capacity to do so.
The bumblebee sting is generally less painful than that of a honey bee or wasp. However, unlike those insects, the sting apparatus is not barbed but rather retracts back into the bumblebee’s body after use. As a result, bumblebees can sting more than once during their lifetime.
But there’s also another key difference in this realm between bumble bees and other types of bees. Only the female bumblebee has a stinger. Males of the species sport a genital capsule, for reproductive purposes, where the stinger would normally be found. These capsules vary from sub-species to sub-species and on a microscopic level are often used to differentiate between the different types of bumblebees.
Another advantage of the non-barbed design of a female bumblebee’s sting apparatus is that it ties into a much longer lifespan.(2) When non-reproducing female honey bees sting something, their apparatus gets stuck in the prey because of the barbed design. As the honeybee tries to free itself, its sting and venom sac are ruptured from its body, resulting in a quick death. Not so for the bumble bee, for the simple reason that their stinger does not get stuck in their prey.
There are roughly 300 different kinds of bumblebee worldwide, each favoring a temperate climate. Like other kinds of bees, the bumblebee has found itself increasingly threatened by pesticides and the encroachment of manmade structures or development into its natural nesting areas. At the moment, in some countries, a full quarter of all bumblebee species are on the corresponding endangered species list. And because bumblebees have longer tongues and a better at “buzz pollination” (the practice of vibrating pollen off antlers), they can better pollinate certain types of plants, like tomato plants.
(1) Bumblebee.org – The Bumblebee Sting, Retrieved September 26, 2011 from http://www.bumblebee.org/bodySting.htm
(2) International Bee Research Association (IBRA) – FAQ, Retrieved September 26, 2011 from http://www.ibra.org.uk/categories/faq