Here is what a honeybee swarm looks like. Swarms are most common in the spring, but can happen all summer. Bees are at their most docile mood while swarming.
Here is text from “It’s Swarm Time!” an article from The Utah Pest News, produced by the Utah Plant Pest Diagnostic Lab and Utah State University Extension. You can find this article at http://utahpests.usu.edu/htm/utah-pests-news/summer2011/
A honey bee swarm can be an impressive, and sometimes intimidating, sight, as a huge cloud of bees (sometimes as large as the size of a suburban backyard) flies from a crowded bee colony to a new location. There were many reports of honey bee swarms in northern Utah this spring from anxious homeowners. A better understanding of swarming behavior should alleviate concerns anyone may have when encountering a swarm. In the spring, a honey bee colony will rapidly build up its resources and produce a lot of brood. Often this leads to cramped conditions by late spring or early summer. In response, the colony will split into two, and the new colony relocates, a process also known as swarming. The process begins with the rearing of a new queen. Simultaneously, scouts begin looking for a suitable location for a new hive. Hollow trees are a favorite, but any large cavity is a potential new home. About 30 to 70% of the worker bee population will engorge themselves with honey before leaving so that they will have plenty to eat as they search for and establish a new home. Once the new queen has matured, she stays with the existing colony and the old queen and worker bees leave to start the new hive. Soon after departing, the old queen will land on an object as a temporary staging area. The worker bees will orient to the queen’s pheromones and surround her. The result is a huge ball of bees that can sometimes be located in a backyard tree. The scouts that had previously located potential new nesting sites try to “convince” the hive to move to their chosen site. After a few hours, a decision is reached and the swarm departs. Witnessing the bees’ arrival or finding a swarm may cause unnecessary panic. Swarming bees are actually much more docile than bees in a hive. Their main concern is keeping the queen safe and warm and relocating the hive. The worker honey bees are still engorged and will have a difficult time stinging. I have walked right up to a swarm and held my hand within an inch of the bees with no consequence. They have no brood or honey to protect in this situation, and thus, are calmer. Homeowners concerned about a swarm may contact the Utah Beekeepers Association, which maintains a list of beekeepers that are interested in collecting swarms. A local beekeeper may agree to come out to the residence and collect the swarm, to the mutual benefit of all.
-Cory Stanley, USU CAPS Coordinator
Delaplane, K. S. 2007. First lessons in beekeeping. Dadant & Sons, Inc., Hamilton, IL. 166 pp.
Shimanuki, H., K. Flottum, and A. Harman. 2007. The ABC & XYZ of bee culture. A.I. Root Company, Medina, OH. 911 pp.d z