Fire ant flights in the US South: why autumn isn't too late

A warm September afternoon can still bring flying fire ants to a southern US lawn. In Mississippi, the extension service describes a swarming season running from spring through late fall, with flights especially common a day or two after rain following a dry spell. An autumn swarm fits that account. Mississippi State University's fire-ant biology guide explains the sequence.

Red imported fire ants, Solenopsis invicta, are not confined to one spring flight and one autumn flight. Burns, Vander Meer and Teal's 2007 study of wing shedding describes mating flights as possible at any time of year when conditions are right. Vogt, Appel and West's flight study likewise describes year-round potential, with most winged ants flying in spring and summer.

These accounts cover different aspects of the season. They support watching for autumn flights; they do not establish a separate September–October peak everywhere in the South. Nor does a flight in spring mean a colony has used up its year's reproductive activity.

Winged reproductive ants leave established colonies to mate. The workers stay on the ground. After landing, newly mated queens shed their wings and may try to establish a nest in the soil. A swarm overhead can include ants that came from beyond your yard, so it does not locate the parent mound. Mississippi State's account describes both aerial dispersal and colony founding.

Rain is a useful reason to pay attention, especially after a dry period. It cannot tell you that a particular mound will release ants tomorrow. Record the activity you see: winged ants gathering outside an entrance, ants taking off, or queens walking on the ground afterwards.

That last observation needs care. A walking queen does not tell you the hour she flew. Missing wings do not prove she mated, either: Burns and colleagues describe wing shedding in unmated females separated from the colony queen. A photograph and an honest account of where you found her are more useful than an assumed mating history.

Fire-ant workers sting, and disturbing a mound brings them out to defend it. Keep your hands and feet away from the mound while photographing activity; do not open it to look for winged ants. Mississippi State's account of fire-ant stings describes their defensive behaviour.

If you're unsure which ant you saw, leave the species name uncertain. A reddish ant in the southern United States is not enough for a species identification. Keep the original photographs, the observation time and the location together. When you report a sighting, describe whether you watched a flight or found an ant after it had landed.