All honey bees live in colonies where the workers will sting intruders as a form of defense, and alarmed bees will release a pheromone that stimulates the attack response in other bees. The different species of honey bees are distinguished from all other bee species by the possession of small barbs on the sting, but these barbs are found only in the workers. The sting and associated venom sac are also modified so as to pull free of the body once lodged (autotomy), and the sting apparatus has its own musculature and ganglion which allow it to keep delivering venom once detached.

It is presumed that this complex apparatus, including the barbs on the sting, evolved specifically in response to predation by vertebrates, as the barbs do not usually function (and the sting apparatus does not detach) unless the sting is embedded in fleshy tissue. While the sting can also penetrate the flexible exoskeletal joints in appendages of other insects (and is used in fights between queens), defense against other insects such as predatory wasps is usually performed by surrounding the intruder with a mass of defending workers, who vibrate their muscles so vigorously that it raises the temperature of the intruder to a lethal level.

The European hornet Vespa crabro is the largest European eusocial wasp, commonly known simply as the "hornet". This is not to be confused with the colloquial use of hornet for the bald-faced hornet, or other yellowjackets in other countries. The queen measures 25 to 35 mm long, males and workers are smaller. In males, as in most members of the Aculeata, the antennae have 13 segments, while in females there are only 12; also as in other aculeates, the male abdomen has seven visible segments, while the female has six; females possess an ovipositor modified into a sting which is not barbed. See wasp and bee characteristics to help identify similar insects.

This species is not particularly aggressive except when defending the nest, and care must be taken when in proximity, as the stings are quite painful. As with most stinging insects, they will sting in self-defense when grabbed or stepped on.

European Hornets are often (although wrongly) thought to be very aggressive and dangerous, and are greatly feared by some people. Some people believe that "three stings from the European hornet can kill an adult human, and that seven can kill a horse". These are common myths - a sting from a European hornet isn't any more dangerous than a wasp sting, and hornets are less aggressive than wasps. In contrast, multiple Asian hornets stings are, in fact, more dangerous.