structural:expansion
As an environmental threat

Some entomologists have observed that non-native, feral western honey bees can have negative impacts within their non-native environment. Imported bees may displace native bees, and may also promote reproduction of invasive plants ignored by native pollinators.

Honey bees are not native to the Americas, arriving with colonists in North America in the 18th century. Thomas Jefferson mentioned this in his Notes on the State of Virginia:

The honey-bee is not a native of our continent. Marcgrave indeed mentions a species of honey-bee in Brasil. But this has no sting, and is therefore different from the one we have, which resembles perfectly that of Europe. The Indians concur with us in the tradition that it was brought from Europe; but, when, and by whom, we know not. The bees have generally extended themselves into the country, a little in advance of the white settlers. The Indians therefore call them the white man's fly, and consider their approach as indicating the approach of the settlements of the whites.

Sources may claim that honey bees (Apis mellifera) have become an invasive species in the United States, outcompeting native pollinators for food. However, while the USDA lists Africanized honeybees (Apis mellifera scutellata) as an invasive species, it does not classify western honey bees as invasive.

With an increased number of honey bees in a specific area due to beekeeping, domesticated bees and native wild bees often have to compete for the limited habitat and food sources available. Western honey bees may become defensive in response to the seasonal arrival of competition from other colonies, particularly Africanized bees which may be on the offence and defence year round due to their tropical origin. In the United Kingdom, honey bees are known to compete with native bumblebees such as Bombus hortorum, because they forage at the same sites. To resolve the issue and maximize both their total consumption during foraging, bumblebees forage early in the morning, while honey bees forage during the afternoon.

A 2017 systematic review looked at the impacts of managed bees on wild bee populations. In addition to honey bees, this includes bumble bees and some solitary bees. The analysis looked at resource competition and changes in plant communities. It also discussed how managed bees may interact with wild bees by transmitting pathogens. It found an equal number of studies reporting both positive and negative effects on plant communities. Studies examining resource competition had significant variability in their results while most studies on pathogen transmission pointed to potentially detrimental impacts. The researchers noted that most studies documented the possibility of certain interactions without actually measuring the direct effects.

The very generalized nature of the honey bee's nectar-gathering activities, potentially visiting dozens of different species in a single day, means that a flower visited by a honey bee will often get very little pollen from its species. This diminished pollination can reduce the plant's ability to produce seeds, especially when the honey bees are squeezing out the native pollinators for a species, a problem occurring all over the United States because of honey bees and other invasive species.

Most flowering plants depend on specialized pollinators to efficiently fertilize them. Cucurbits, for example, are pollinated by squash bees that specifically visit the early-blooming male flowers before sunrise, when honey bees are inactive, and then return to pollinate the female flowers later in the day. Such symbiotic relationships also mean that the specialized pollinator will be covered mainly in its host's specific pollen. Unlike native bees, they do not properly extract or transfer pollen from plants with pore anthers (anthers which only release pollen through tiny apical pores); this requires buzz pollination, a behavior rarely exhibited by honey bees. Honey bees reduce fruiting in Melastoma affine, a plant with pore anthers, by robbing its stigmas of previously deposited pollen.