This article was published originally on 9/29/2010
It's been the best of times and the worst of times for swarming ants this year, depending on your point of view. We have had numerous calls, messages and observations of ant swarmers filling the air. Swarmers are ants that developed in their colony with wings (unlike the millions of wingless worker ants you see on the ground). If you are an ant, this is the best time of the year - the fruits of your labor are flying off to perpetuate the species. If you are a person who does not like winged ants, this is the worst time of year.
Winged swarmers are sexually developed, male and female ants that serve as emissaries from a healthy, well-established colony. Swarmers depart from the established colony on a mission to initiate new colonies. They have very, very slim chances of success. Most will die of starvation, dehydration or will be eaten by birds, dragonflies or other predators. Though almost all will fail, just enough succeed to spread the species and ensure its survival.
All species of ants are capable of producing swarmers. The conditions have to be just right for this to be accomplished. Swarming occurs at different times for different species and each species has a rather predictable time when the swarmers will occur. Foundation ants and field ants, for example, almost always swarm in the fall and at dusk.
Winged ants are visible and easy to notice, but they are harmless. They are not the individuals that did the work of creating mounds in your lawn, dirt piles on your driveway or sawdust at the base of your hollow tree. Swarming is a temporary, natural event and is not a permanent or major problem. Besides, swarmers are often beneficial as an important link in the ecosystem food chain. See the articles from August 25, 2010 and August 26, 2009 for more information about dragonflies feeding in a frenzy on ant swarmers and other flying insects.
Outdoors, ignore swarmers if possible. Indoors, winged ants may be a nuisance or annoyance if they have emerged in the house or wandered in by mistake. There is little justification for treating winged ants beyond sweeping or vacuuming them up for disposal.
When ant control is necessary, direct nest treatment or baiting to control the wingless workers and the egg-laying queen within the colony will be much more effective. Swarming may be your indication of the colony location. It might also be your wakeup call to start looking for an established colony that might be a problem.
Female carpenter ant swarmer; 5/8 inch long. Photo by Donald Lewis.