It is a partial (and rather popular) misconception that bees can only sting once and then die out after one shot. This is only partially true regarding honey bees whose barbed stings often gets left behind. In fact other species of bee, like for example the bumble bee, has been known to sting more than once, as opposed to the honey bee which usualy leaves the stinger on its victim's body.[1][2]

The primary reason for this is that a worker honey bee's sting has small barbs (bumble bees, queen bees and many other stinging insects have smooth stings) which often gets caught when it stings an animal with thick skin.

These barbs are believe to have evolved for the purpose of combat with other insects, the barbs making it easier for the honey bee to penetrate the hard exoskeleton of their opponents.[3]



If a honey bee was able to remove their sting from a victim (for example if the sting was not that deep) then it is highly likely that it will attack another time.

The barbs of the sting was an evolutionary advantage from the perspective of the honey bee against other insects (another colony perhaps that enter their territory or against wasps that often kill bees for food) but against mammals this advantage works against them.

Sources:

http://web.archive.org/web/20071230082748/http://www.straightdope.com/mailbag/mbeesting.htm

http://beespotter.mste.illinois.edu/topics/stings/

http://en.wikipedia.org/wiki/Bee_sting