There are indications that the species is rare, if not extinct in the wild in Europe and as of 2014, the western honey bee was assessed as "Data Deficient" on the IUCN Red List.

Numerous studies indicate that the species has undergone significant declines in Europe; however, it is not clear if they refer to population reduction of wild or managed colonies.

[9] These adaptations include synchronizing colony cycles to the timing of local flower resources, forming a winter cluster in colder climates, migratory swarming in Africa, and enhanced foraging behavior in desert areas.

[14] In most climates, western honey bees swarm in the spring and early summer, when there is an abundance of blooming flowers from which to collect nectar and pollen.

Throughout the rest of the growing season, the colony produces many workers, who gather pollen and nectar as cold-season food; the average population of a healthy hive in midsummer may be as high as 40,000 to 80,000 bees.

Nectar from flowers is processed by worker bees, who evaporate it until the moisture content is low enough to discourage mold, transforming it into honey, which can then be capped over with wax and stored almost indefinitely.

Like other insects that undergo complete metamorphosis, the western honey bee has four distinct life stages: egg, larva, pupa and adult.

In the absence of flavonoids and the presence of a high-protein diet, female bees grow into queens by developing the vigorous reproductive system[21] necessary to maintain a colony of tens of thousands of daughter workers.

In temperate regions, drones are generally expelled from the hive before winter, dying of cold and starvation since they cannot forage, produce honey or care for themselves.

Western honey bees can forage over a 30 °C (86 °F) air-temperature range because of behavioral and physiological mechanisms for regulating the temperature of their flight muscles.

[citation needed] Western honey bees also change the precision of the waggle dance to indicate the type of site that is set as a new goal.

[40][41] When the duration of trophallaxis pairings was measured, it was found that like human social interactions, there are durable long-term trends for each individual bee.

Further, they argue that the difficulty of controlling drones for mating is a serious handicap and a sign that domestication is not complete, in particular as "extensive gene flow usually occurs between wild/feral and managed honeybee populations".

The nectar, transported in the bees' stomachs, is converted with the addition of digestive enzymes and storage in a honey cell for partial dehydration.

While this can protect the colonies from extremes of temperature and make winter care and feeding more convenient for the beekeeper, it increases the risk of dysentery and causes an excessive buildup of carbon dioxide from the bees' respiration.

Roger Morse and Nicholas Calderone of Cornell University attempted to quantify the effects of the western honey bee on American food crops.

Propolis is a resinous mixture collected by honey bees from tree buds, sap flows or other botanical sources, which is used as a sealant for unwanted open spaces in the hive.

[77] The genome is unusual in having few transposable elements, although they were present in the evolutionary past (remains and fossils have been found) and evolved more slowly than those in fly species.

The increased genetic diversity resulting from high recombination rates could make the workers less vulnerable to parasites and facilitate their specialisations to different tasks in the colony.

[79] Western honey bee populations face threats to their survival, increasing interests into other pollinator species, like the common eastern bumblebee.

[80] North American and European populations were severely depleted by Varroa mite infestations during the early 1990s, and U.S. beekeepers were further affected by colony collapse disorder in 2006 and 2007.

[83] Improved cultural practices and chemical treatments against Varroa mites saved most commercial operations; new bee breeds are beginning to reduce beekeeper dependence on acaricides.

The pollinia may also stick to the bee's tarsal claws, causing a lack of climbing ability and honey gathering which may result in expulsion from the colony leading to death.

Native butterflies, moths, flies, beetles, bees and wasps are common milkweed visitors which are often able to escape without issue, though some species of Megachile, Halictus, Astata, Lucilia, Trichius, Pamphila and Scepsis have been found dead on the flowers.

After removing over 140 dead bees from a patch of A. sullivantii, entomologist Charles Robertson quipped "... it seems that the flowers are better adapted to kill hive-bees than to produce fruit through their aid.

"[86] Insect predators of western honey bees include the Asian giant hornet and other wasps, robber flies, dragonflies such as the green darner, some mantises, water striders and the European beewolf.

The egg-yolk protein Vitellogenin (Vg) plays an important role in TGIP in honey bees, as it participates in the information transmitted between queen and offspring.

By exhibiting a grooming dance, other nest mates are attracted and assist to remove parasites via stroking with antennae or legs and licking.

[91]Sources may claim that honey bees (Apis mellifera) have become an invasive species in the United States, outcompeting native pollinators for food.

Honey bees reduce fruiting in Melastoma affine, a plant with pore anthers, by robbing its stigmas of previously deposited pollen.