Holes and cracks in concrete allow bees to move freely from ground or tree nests into structures where bees can build large, complex nests that pose health, safety and property damage risks. As a result, removal of bees from concrete is extremely important to closing a potential "gateway" into human habitations. Because most bees help the environment but some can pose life-threatening hazards, killing bees or attempting removal without professional aid aren't viable options. Instead, to get rid of bees in your concrete, you must obtain the aid of a professional bee remover, beekeeper and/or pest exterminator.
Make a list of the areas around your property and/or structures where you have observed bees in concrete. In addition, search for tree nests and bees exiting and entering ground holes, and mark these areas on your list. If you find bees around a home or other living space, put on a pair of protective goggles and carefully check attics, walls and crawlspaces. If you have a bee allergy or suspect that you're dealing with Africanised honey bees (AHBs), skip this step entirely.
Contact a professional to remove the bees. Not only are some species of bees protected because of concerns about bee population decline and its impact on the environment as well as commercial honey production, but many bees also attack in swarms with little to no provocation---capable of killing small children, pets and even adults. Professional bee removers and beekeepers can recognise different bee types and know the best removal methods. Many pest exterminators also refer back to local beekeepers when dealing with bees and, as opportunistic insects often inhabit areas around nests--especially if honey is involved--an exterminator can also help remove such insects once the beekeeper has removed the bees.
Get rid of the bees by allowing the professionals to work unhindered. This may require that you leave your home or property for a time while the professionals remove the bees or nest, spray insecticide against other insects or a home or property insurance inspector reviews the damage caused by the bees. Once you have the bees removed, follow all beekeeper and/or exterminator instructions in regard to preventing future bee infiltration.
Seal all concrete surfaces, including holes, cracks and crevices, with a concrete crack filler product to protect against new bees or insects entering the concrete.
Always maintain any concrete around your property---fill holes, cracks and crevices. Doing so can not only prevent and protect against bee infiltration, but also help extend the life of the concrete and any structures built with it. Never use insecticide or mothballs to get rid of bees in concrete--you may scare the bees further into the concrete or cause the bees to swarm. In addition, killing a few bees that you see rarely solves the problem, as a larger bee nest likely exists---outside or perhaps inside a nearby structure---close to the area where you saw the bees. Never knock on walls that you suspect contain bees or use a hose to spray water into nests to "drown" the bees. Either action can incite bees to swarm.