MISSISSIPPI STATE -- If it looks like a basketball is stuck in a tree or bush this April, better check closely before knocking it out -- it may be a swarm of thousands of honey bees.

Honey bees start to swarm in mid-March in South Mississippi, and by the end of April they are swarming in the northern part of the state. Doug Stone, a beekeeper and Mississippi State University research associate in forest entomology in the Department of Entomology and Plant Pathology, said bees swarm just before the nectar starts to flow in plants.

“The queen has laid a lot of eggs, the hive population is high and they are very crowded in the spring,” Stone said. “The old queen leaves, and as many as half the bees leave with her.”

Stone said swarming is one way bees sustain their population in an area. Worker bees start the process by developing a new queen.

“A worker takes an egg from a worker cell and moves it to a larger queen cell or a queen can lay an egg in a queen cup where they are fed royal jelly for numerous days,” Stone said. “This royal jelly develops the larva into a queen.”

When it is time to leave, the old queen stops laying eggs so her enlarged body can shrink enough that she can fly. She and the swarm leave the hive and cluster up nearby while scout bees find a new home.

“The scout bees look for cavities in hollow trees, eaves on houses, old barns, silos, woodpiles or even 55-gallon drums,” Stone said. “Once several scouts agree on a new hive location, they communicate to the cluster where the cavity is, and the entire swarm leaves.”

Stone said this cluster of bees is relatively harmless and will leave in days, if not hours. He encouraged those with a swarm of bees to just leave them alone. If the swarm is easily accessible from the ground, a beekeeper may want to come collect them.

“A good way to find a beekeeper in the area is to contact the county Extension office or police and fire department as they keep lists,” Stone said.

Bees that are simply swarming are not a problem, but those that get in houses are trouble.

“They present a safety hazard, are a nuisance, and can cause damage to the structure and the walls,” Stone said.

The best approach to the problem is to prevent bees from ever gaining access. Stone recommended homeowners inspect the house's exterior every January or February. Seal any crevices, such as cracks around the chimney, warped boards or siding, loose or hanging eaves, or cuts in the brick where pipes or lines have been installed.

“Bees can enter small spaces and may crawl several feet to find a major void where they can make a hive,” Stone said. “Combat them as quickly as possible, as the longer you wait, the more their population builds. The problem gets worse as honey and comb accumulate.”

Stone said most beekeepers will not do construction, and will not try to remove a hive from inside the structure of a building. These bees must be destroyed, and contrary to what some people think, it is not illegal to kill honey bees.

“Exterminators will have some type of aerosol spray or pressurized dust that can effectively destroy the hive no matter where it is located,” Stone said.

Clarence Collison, head of MSU's Department of Entomology and Plant Pathology, said a well-established beehive within a building is a big problem. His department recommends homeowners hire a licensed pest control firm to do the extermination.

“Not every pest control business will handle stinging insects, so you may have to call around to find one that will,” Collison said.

Eliminating the problem involves more than killing the bees.

“If you kill off the bees but don't remove the comb and wax, you will have secondary problems with insects such as ants and wax moths entering the area to feed on honey and wax,” Collison said. “Also, since bees regulate the temperature inside the hive, once the bees are dead, the hive may heat to the point that the wax and honey melts. This could drip or ooze out of the walls and require extensive renovation to remove and clean up.”

Don't forget to seal the bees' entryway, or another swarm could move in next year.

MSU Extension Service Information Sheet 1662 gives more information on dealing with honey bees in houses, and is available from local county Extension offices or online at http://www.msucares.com. Beekeeper information is online at http://www.mshoneybee.org.