Honeybees (Apis mellifera) are common in this country, but they are not native. They were introduced from Europe, and have become a naturalized part of our insect fauna. Honeybees are of considerable economic importance because they pollinate many of our crop plants; it has been estimated that the pollination services of honeybees are worth billions of dollars per year. People keep domesticated hives of bees for pollination purposes, and commercial hives are transported around the country to places where their services are needed. In addition to their activities as pollinators, honeybees provide honey, which is essentially processed nectar. Honeybees have a "honey stomach", which is an expanded part of their midgut. Nectar is collected from flowers and passes into the honey stomach. Water is removed and eventually a concentrated material, the honey, is regurgitated into the honeycomb. Honey is the energy source for the bee hive. Foraging bees also collect pollen; it is used to feed the developing larvae. Pollen is processed into "bee bread" which provides protein and other nutrients not present in honey, which provides only carbohydrates (sugars).

Honeybees are eusocial, which means they have cooperative brood care, reproductive division of labor, and overlap of generations. A honeybee hive is perennial, and may contain between 20,000 and 80,000 workers. The activities of a bee hive are controlled pheromonally by the queen. The queen is the mother of the workers, who are sisters. The adult workers care for their developing younger sisters, the brood. Development of the larvae is controlled by pheromones. Larvae that receive the "queen substance" develop into workers. Some larvae are fed "royal jelly" so that they develop into new queens. The mother queen also lays unfertilized eggs, which will develop into haploid males, the drones (see below). New queens and drones are produced when a bee hive becomes large and crowded. The old queen will take a large number of workers and "swarm", which means they leave the original hive and start a new one elsewhere. Swarming typically occurs in the late spring or early summer. The original hive has plenty of workers, and one of the new queens will mate with drones (from other hives) during a series of "nuptial flights", and return to "assume command" of the original hive.

Worker bees are monomorphic (meaning they are all the same size) and there is no soldier caste in honeybees. However, the workers change the tasks they do as they age. Young adult workers do mostly "innendienst" (meaning inside work). This includes care of the brood, tending the queen, making beebread, processing nectar, and constructing the comb. Older workers do "ausendienst" (outside work) which is primarily foraging but also defense of the hive and searching for new locations for swarming. Honeybees sting in defense of the hive. Their stinger is like a small hypodermic needle, and it has barbs that lodge it into the skin of the intruder. This causes the entire stinger apparatus (the stinger itself, the associated venom gland, and musculature) to pull out of the back of the honeybee's abdomen, which kills the bee. The stinger, however, continues to pump venom into the intruder's body. Some people are quite allergic to bee stings; in this country more people die each year from bee stings than from snake bites.

Honeybees, like all Hymenoptera, are haplodiploid (the males are haploid, the females are diploid). Because of this unusual sex-determination mechanism, the workers, who are sisters, are related to one another by 0.75 rather than 0.5, so they are better off genetically to help their mother (the queen) produce additional sisters than they would be to produce their own offspring (to whom they would be related by only 0.5). This is the primary argument why eusociality has evolved repeatedly in the Hymenoptera, and why honeybees (and all other eusocial hymenopterans) are so dramatically altruistic.