In the United States, most fire ant bites are caused by either red imported fire ants (RIFA) or black imported fire ants (BIFA). We often call them "fire ant bites," but do fire ants bite or sting you? The answer is yes to both.
With both RIFA and BIFA, the welt or pustule that develops is not the result of a fire ant's bite, but rather their sting. Both of these species of ants, when angered or threatened, will swarm over the perceived threat – crawling up to 0.63 inches per second – and begin to attack. The ant will use its mandibles to bite down on the offender and give itself leverage in order to use its stinger. Once latched on, an ant can pivot around that site, stinging multiple times. This is why "fire ant bites" may sometimes appear in a circle.
Fire ants bite to protect their home, and those that are able to do so are queens and sterile female workers. Queen ants have both a stinger and an ovipositor for laying eggs. Sterile female workers also have ovipositors, but theirs have adapted to inject venom into their enemies. Male ants are unable to sting.
The venom produced by RIFA and BIFA is made up of alkaloids and proteins. The alkaloids cause cell death at the sting site, resulting in an influx of white blood cells as the body tries to repair the damage. This is what forms the pustule that is associated with a fire ant bite. The proteins in the venom, which are less than 1 percent of its makeup, are harmless for most people. However, in people who are sensitive to these compounds, serious reactions – including anaphylactic shock – can occur as a result of one or more stings.
According to the American Osteopathic College of Dermatology's website, stung by fire ants fall into three categories. In the majority of cases, people develop a small welt, followed by a pustule, and symptoms will clear up completely in around one week. The website states that those few who fall into the second category may experience a more severe reaction that results in a larger welt and possible swelling at the site of the sting. The final category includes people who have a severe allergic reaction to fire ant venom. If you are sensitive to insect venom and experience fire ant bites, you should seek immediate medical treatment to prevent complications due to your exposure.
Most people who are stung by fire ants will experience no lasting after effects.
Avoiding fire ant nests and areas where you suspect these insects are foraging can help you avoid fire ants' bites too.
While many ant mounds are visible, keep in mind that there may be smaller mounds hidden in grass. RIFA and BIFA nests are also sometimes built under debris, rocks or woodpiles. If left undisturbed, the ants should not bite you. Most bites occur when people do not pay attention and stand on the ants' mound or in their forage area.
If you do come across RIFA or BIFA, the first step is to remove the ants that are stinging you. The Centers for Disease Control's National Institute for Occupational Safety and Health (NIOSH) factsheet on stinging insects lists the following methods for treating fire ant bites:
Rub off ants briskly, as they will attach to the skin with their jaws.
Antihistamines may help.
Follow directions on packaging.
Drowsiness may occur.
Seek immediate medical attention if a sting causes severe chest pain, nausea, severe sweating, loss of breath, serious swelling, or slurred speech.
Now that you know what to do if you experience a fire ant bite, you can turn your attention to keeping ants out of your yard. If you have concerns about the best method of control for your fire ant problem, call a pest management professional.