Bee Informed: Warming and Swarming

What is honey bee swarming?

When it comes to colonies and queens, there can be only one. The queen bee in an active hive is rarely seen outside and hardly ever needs to fly. She stays deep inside the comb, is cared for by the worker bees, and continually lays eggs. Honey bee queens produce a pheromone that inhibits the production of new queen bees.

But as colonies become increasingly crowded the message fails to make it to all the bees, or older queens begin to produce lower levels of the pheromone. Uninhibited worker bees create larger elongated rearing cells called queen cups. Once eggs in the queen cups hatch the larvae are given special care and are fed with a food called royal jelly. Worker bees tending the existing queen give her less food, and egg production slows as the queen loses body weight, which will ultimately help her to fly. When new queens are almost ready to emerge from the queen cups, the old queen takes most of the workers and departs. The traveling mass of bees is called a “swarm”.

Before leaving, the workers fill their stomachs with honey, and this is the only food the swarm has to sustain activity until they find a new home site in which to establish their new colony. The old queen, being a weak flyer will often land suddenly, and often not far from the original hive. Resting swarms can be found clustered on the ground, on a fence post, a tree limb, or the side of a building (Fig. 2), and workers will quickly surround the queen to regulate her temperature. Since swarming bees are focused on finding a new home, they are not generally defensive and rarely pose any danger to humans or other animals. Swarming is common during spring and continues throughout the year while pollen and nectar sources support growing colonies. This is greatly influenced by environmental conditions. In the low desert southwest, plants are already blooming, and bee experts report that wild honey bee swarming began weeks earlier than usual.

Back in the original hive, the first queen to emerge will sting and kill other emerging queens. The old hive usually has enough food reserved to last the colony for a while, but it is important to start building up the number of worker bees once more. The new virgin queen will mature after several days and fly out to seek drones in areas called “drone aggregations”. She will mate multiple times with several drones and will store sperm for the remainder of her lifetime. After mating, she will return to the hive and start laying eggs, slowly building up the colony.
Sometimes newly emerged virgin queens will leave the hive with a group of workers in another swarm, called an
“after swarm”, and this can occur repeatedly until the old hive is depleted and dies off.

How to identify a swarm?

If a cluster of bees suddenly appears on a wall, on a branch of a tree or on the ground and remains exposed, this is most likely a resting swarm. Swarming bees will not have yellow or orange pollen evident in pollen baskets on their hind legs, and swarms will not be seen moving in and out of cavities. Swarms will often move on in a few days without intervention and although not defensive, they can sting if disturbed. It is best to observe the swarm from a distance and hope they do not find suitable nesting sites close to or in your home or building.

What to do when you see a swarm?

It is best to leave swarms alone if they are in a spot that does not have much human traffic passing close by, e.g., a swarm on a wall that can be cordoned off using caution tape. But if a swarm is in the way of people in a location that cannot be avoided, seek the help of an experienced professional to remove swarms. If swarms are disturbed, they will disperse within a local area and this can cause people to panic.

Have staff or contacted pest management professionals who can respond rapidly to wild honey bee swarms when necessary. Local beekeepers or beekeeping associations often help. Most states have their own beekeeper’s association, and many are active on social media. Some beekeepers will collect swarms and use them to start new hives. Information for the Arizona Beekeepers Association can be found at https://www.azbeekeepers.org/. The website provides a list of beekeepers that might be able to assist with bee removal.

Wild honey bee colonies

Compared to swarms, established colonies in and around homes, schools, and other buildings pose greater risks to people (Fig. 3 and 4).

Wild honey bees can become pests because of sting incidents, defensive bee attacks, and the structural damage and annoyance that their foraging and nest-building activities can cause. The chances of people getting stung in such situations are much higher once brood are being reared.

Bees and combs should be removed by professionals who have appropriate personal protective equipment.

Most honey bees observed in the landscape are foraging bees from established colonies looking for water, nectar or other sugary, sweet-smelling substances. If you observe bees passing in and out of a cavity, this indicates the presence of a colony within.

Honey bees and other pollinators are important and desirable elements in our natural environment. But wild honey bees can sometimes interfere with our activities or interests.  When this happens the best course of action is to take an integrated pest management (IPM) approach.