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The Fire Ant Sting

Fire ant stings cause a white pustule that lasts for many days.
Fire ant stings cause a white pustule that lasts for many days.

Anyone who has ever been unfortunate enough to have an intimate encounter with fire ants understands why they are such unwelcome pests. They sting and it hurts!

Fire ants bite as well, grasping the skin with their mandibles to anchor themselves and better insert their sting. The bite is of no lasting consequence, but the venom they inject through their sting is quite potent, especially in relation to their size. Unlike the sting of the honey bee, the sting of the fire ant is not barbed, and an individual worker can sting repeatedly and still survive to return to her normal duties.

Initially, there is a sharp localized pain. Within about 24 hours a raised white pustule forms at the site, and this will persist for many days. Despite the appearance of this pustule, it is not infected. Stings can cause localized pain and/or itching for several days, and they can potentially become infected, especially if broken open by scratching or other causes. The potential for secondary problems is greater in people suffering from medical problems, such as diabetes or compromised immune systems.

For most people a single fire ant sting is a ‘mildly painful’ experience that would quickly be forgotten were it not for the ‘mildly irritating’ pustule. Unfortunately, a stinging encounter with fire ants usually involves more than one ant, and each year many people have the experience of being stung by dozens, or even hundreds, of fire ants. The pain and irritation associated with a single sting is multiplied many fold in such incidents. Most people recover from such encounters with no lasting ill effects, and it is only when such stinging incidents involve many hundreds or thousands of stings that they become truly threatening. But incidents of this magnitude do occasionally occur, usually involving people who are less mobile due to age, accident or infirmity.

Although a few fire ant stings do not constitute a medical emergency for most people, a very small percent of people develop allergic reactions to fire ant venom. These vary in intensity, but in the most extreme cases even a few stings can result in the life-threatening condition known as anaphylaxis. Each year there are cases of human fatalities resulting from fire ant stings, either due to anaphylaxis or to massive numbers of stings occurring on people who are incapacitated.

Given the pain and discomfort that can result from even a few fire ant stings, it is fortunate that fire ants do not normally aggressively seek out and attack human beings. The vast majority of stinging events occur when people inadvertently ‘attack’ the fire ants, usually by unknowingly stepping in, lying in, or otherwise disturbing the mound. The ants perceive this disturbance as a direct attack and the workers quickly react en masse to defend their colony.

Lesion Development:

Fire ant stings cause a white pustule that lasts for many days.

Images linked below are used in the animated photos of a person's finger after a fire ant sting:

  • Stinging photo: A worker female fire ant in the act of stinging a human thumb.
  • 30 minute photo: There is a slight swollen bump where each sting occurred, surrounded by redness.
  • One hour photo: The bumps persist, and the surrounding redness gets deeper red.
  • 24 hours photo: A pustule is now present where each sting occurred. Lesions are still surrounded by a deep red halo.
  • 72 hours photo: Pustules are at their peak, with a deep red halo, and some tissue death inside the tiny pustule domes.
  • One week photo: By now the pustules have ulcerated; the red halo persists.
  • One month: Only superficial scars remain where the stings occurred.

Contact

Dr. Blake Layton, Extension Entomology Specialist
Department of Entomology, Mississippi State University
Phone: (662) 325-2085
Email: blayton@entomology.msstate.edu

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News

Fire ant mounds are common along fence lines where they are protected from grass-cutting equipment and other traffic, such as this mound in an Oktibbeha County, Mississippi, pasture on May 11, 2015. (Photo by MSU Ag Communications/Kevin Hudson)
Filed Under: Forages, Insects-Forage Pests, Fire Ants May 19, 2015

STARKVILLE, Miss. -- Southern farmers may never win the battle against imported fire ants, but aggressive tactics can slow the pests’ invasion, reduce damage and prevent further spread across the United States.

Jane Parish is an Extension/research professor with the Mississippi State University Extension Service and the Mississippi Agricultural and Forestry Experiment Station. She said cattle and hay producers have learned to live with and work around the troublesome ants since the pests arrived in the state almost a century ago.

The biggest reason people have trouble controlling fire ants is that they only treat individual fire ant mounds. Individual mound treatments can be useful situationally, but need to be supplemented with broadcast treatments that will control all fire ants in all areas. (Photo by MSU Extension Service/Kat Lawrence)
Filed Under: Agriculture, Insects-Crop Pests, Insects-Forage Pests, Insects, Fire Ants, Insects-Pests May 15, 2015

STARKVILLE, Miss. -- People have many misconceptions on how to eliminate fire ant mounds and prevent them from coming back, and these erroneous beliefs hinder efforts to keep the harmful pest from spreading.

Many dogs spend time outside and often share their play areas with fire ants. When disturbed, the ants sting and deliver venom that can cause severe allergic reactions for some pets and children. (Photo by MSU Ag Communications/Susan Collins-Smith)
Filed Under: Fire Ants May 5, 2015

RAYMOND, Miss. -- Fire ants can be more than unwelcome guests in the home lawn; their stings can be dangerous for children and pets who share play areas with the pests.

Fire ant stings are characterized by sharp localized pain, swelling and intense itchiness that is just a short-lived nuisance for most. A raised red bump appears soon after the sting and soon turns into a sterile pustule that resembles a pimple. However, the ants’ venom can cause severe allergic reactions in some people and pets.

Most fire ants found in Mississippi are a hybrid between the red imported fire ant, pictured here, and the black imported fire ant. (Photo by Mississippi Entomological Museum/Joe A. MacGown)
Filed Under: Fire Ants April 24, 2015

STARKVILLE, Miss. -- Tell Mississippians that fire ants have completely invaded the state, and they’ll probably shrug and say they already know that. Tell them the pain actually comes from a sting rather than a bite, and they’ll say it still hurts. But tell them how to get rid of the nasty critters, and they’re all ears.

The Mississippi State University Extension Service is organizing efforts to help residents Bite Back against fire ants. The solution is a simple two-part attack, but success comes in the long-term follow-through.

Closeup -- The invasive fire ant, known for its reddish color and nasty sting, is a common enemy of most homeowners and gardeners in Mississippi. (Photo courtesy of Marina Denny)
Filed Under: Fire Ants July 3, 2014

MISSISSIPPI STATE -- Fire ants are more than aptly named, given the reddish-orange color of their bodies and the painful, burning sting they can give.

Fire ants were unintentionally introduced to the United States from South America. The first documented release of fire ants occurred near Mobile, Alabama around 1918, and by the late 1930s, most of Mississippi had them.

Fire ants are very small and aggressive. When disturbed, they swarm, bite and sting, producing a painful or itchy pustule within hours.

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