Ovipositors are well-developed and modified into a stinger in the Aculeate Hymenoptera. Because the stinger is evolved from the ovipositor (egg-layer) possessed only by females, male wasps are not able to sting.

All social bees and wasps use their stinger to defend the colony. The sting consists of a venom reservoir and three "needles": two barbed lancets and a stylet, linked together to form a hollow tube through which venom can be pumped. The stylet makes the initial penetration, and then the two lancets, which slide on "rails" alongside the stylet come forward to deepen the wound.

Wasps and bumblebees can withdraw the stinger and reuse it, but honey bees have multiple large barbs on their sting; they cannot be withdrawn and the bee sacrifices herself for the colony: when she withdraws, the venom sacs are pulled from her abdomen, resulting in death. The venom apparatus continues to function, however, pumping venom into the wound long after the bee has decamped. [1]

Many humans have developed allergies to bee stings, and can suddenly develop anaphylactic shock, a condition which can kill if not treated quickly.

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