Fire Ant Basics

When it comes to fire ants, pay attention to detail  By:  Dr. Mike Merchant

In case you missed it, last month a 13-year old middle school student died  as a result of fire ant stings he suffered during half-time on a Corpus Christi, Texas football field.  The student, Cameron Espinosa, was on the sidelines when he complained of difficulty breathing after receiving fire ant stings on the field.  He collapsed and died several days later from complications due to an apparent anaphylactic reaction to fire ant venom.

The incident reminds me of how important good pest control is to everyone’s health and well-being. It also gets me thinking about all the things necessary to doing a good job when it comes to fire ants.

I know this school district considered fire ant control important and took steps to control them, but a lot of factors go into controlling fire ants effectively on a football field, or in any sensitive site.  So I thought I would share some things that come to mind when I think about good fire ant control:

  • Know your fire ant insecticides.  Fire ant control insecticides include slow-acting baits (IGRs), faster-acting baits (spinosad, indoxacarb, hydramethylnon), slow-acting residual granulars (fipronil), faster-acting residual granulars (bifenthrin).  You also have a wide variety of products for mound treatments, most requiring water for activation. Each of these products has advantages and disadvantages.  Do you know them? If not, check with your state extension entomologist or a knowledgeable pesticide distributor.
  • Plan ahead.  Baits are less costly than most other treatments and fit in well with goal of using safer materials, especially at a school district.  But baits are slow, most requiring 1-2 months for peak control. Even non-bait, residual granular insecticides require time for control.  The popular Top Choice® granular insecticide (fipronil), requires 1-2 months to eliminate fire ant mounds in the treatment zone. These products are not designed to give good control two days before the first Friday night football game.
  • Know when and how to inspect a field for fire ants.  Fire ants are present in fields all year round, but they are most visible during cool weather, or just after a rain or heavy irrigation.  Inspecting the field at the wrong time could lead to a false sense of security regarding fire ant activity.  In some cases, especially during hot, dry weather, use of hot dog slices (possibly at night) can be the best way to measure fire ant activity.  Also, in the case of athletic fields it’s a good idea to do a final inspection just before a game or practice. Fire ant mounds can appear within just a few hours, especially after a rain.
  • Know how to apply insecticides accurately.  Fire ant baits require specialized equipment designed to put product out at very low rates (generally 1- 1.5 lbs/acre). For large areas a Herd GT-77 spreader is a standard application tool.  Spyker rotary spreaders, or handheld seed spreaders are good for smaller areas. All spreaders should be carefully calibrated to make sure the correct amount is going over the field.  Too much bait and you will overspend on product, too little and you might not get the desired control.  The same is even more true for the more expensive granular residual products.
  • Know when to apply.  Fire ant baits are most effective if applied when ants are actively foraging. When soil temperatures are above 95 degrees F, fire ants stop foraging and retreat deep in the soil.  Baits applied during midday will degrade and lose their attraction before the ants return to the surface at night, when temperatures have dropped.  This means that in the heat of summer fire ant baits should be applied later in the day, just before evening.  Baits are also not effective during the cooler season, so baits applied between October and April, say, may not give you satisfactory control.
  • With baits it’s also important to know the age of the product.  Fire ant baits don’t have an especially long shelf life. So buying fire ant bait when its on sale late in the season for the following year may not be the bargain you think it is.  Buy your bait just before you need it, and only as much as you need.  Saving bait, especially opened containers, from one season to the next, is not recommended. If you are unsure of the quality of a bait, find an active nest and sprinkle some around the base of the mound.  If the bait is fresh the ants should quickly (within 5-15 minutes) pick it up and carry it underground.
  • Don’t rely on just treating mounds to manage fire ant problems.  Mound treatments can effectively kill fire ant colonies, but they do a terrible job of managing fire ant populations in an account.  That’s because it is so difficult to find and treat fire ant mounds. A new fire ant colony may take 6 months to even produce a visible mound.  Broadcast residual treatments or broadcast applications of baits are much more effective because they treat all mounds, visible and invisible.  And they are generally less expensive than mound treatments.
  • Water, water, water. Water is a necessary part of treating individual mounds.  Without it you cannot effectively reach the lower parts of a fire ant nest.  One to two gallons of mixed insecticide, or 1-2 gallons of water to wash in a granular application, are mandatory for good control.  And don’t expect immediate control with all mound treatments.  Aerosols and liquid drenches are fastest, but allow at least an hour with these treatments to ensure that ants in a nest are neutralized.

These are just a few of the details necessary to ensure that you’ve done the best you can to keep your accounts mostly fire ant free.  And remember that schools with athletic fields aren’t the only sensitive sites. Playgrounds, nursing homes and other medical facilities, parks, event grounds servicing thousands of concert goers–all are places where fire ant control needs to be done right.

If you’re a PMP servicing a school or park or a residential lawn, you can’t do this all on your own. Communicate and enlist the help of your customers: coaches, park maintenance staff, or homeowners. Let them know about how to report problems and to know what to do in case of need for an emergency treatment.  And let your customer know about the importance of taking stings–any arthropod sting–seriously.  Anyone who experiences difficulty breathing, tightness in chest or throat, hives or rashes after a sting should seek medical assistance immediately.

Fire ants, like all pests, are an inevitable part of life in Texas.  But that doesn’t mean we have to live with them.

Beware Fire Ant Stings  By, Lucy Li, Ph.D. University of Arizona, Public Health IPM 

Because they are so common throughout the South, fire ant risks are often underestimated.

Because they are so common throughout the South, fire ant risks are often underestimated.

People vary greatly in their sensitivity to fire ant stings. Some may experience very mild discomfort, while others may be hypersensitive to venom or may have medical conditions (e.g., heart condition, diabetes) that can result in serious medical problems or even death from a single sting. Individuals with a history of severe allergic reactions to insect bites or stings should consider carrying an epinephrine auto injector (EpiPen) and should wear a medical identification bracelet or necklace stating their allergy.

Individuals should take the following steps if they are stung or bitten by fire ants:

  1. Remove the stinging ants. The best method is to rub off ants briskly by hand or using a cloth, as they will attach to the skin with their jaws.
  2. Over-the-counter Antihistamines products may help for minor stinging incidents. Follow directions on packaging. Drowsiness may occur.
  3. Seek an emergency medical facility immediately if a sting causes severe chest pain, nausea, severe sweating, loss of breath, serious swelling, or slurred speech. Anaphylactic shock can lead to death.

Avoiding Fire Ant Stings

The best way to avoid medical emergencies associated with fire ants is to prevent being stung. Here are some tips to learn to recognize threatening situations:

  • Look for fire ant mounds. Take care not to stand on or near them.
  • Teach children about fire ant hazards.
  • Alert visitors to your landscape that fire ant mounds are present.
  • Wear protective clothing when outdoor activities taking place near fire ant nests. Wear boots or tuck pant legs into socks.
  • Control ants where they occur in areas used frequently by people and pets.
  • Use insect repellents on clothing or footwear.
  • Use quick defensive reaction. Remove the ants that climb up on your body as quickly as possible.
  • Do not disturb ant nests.
  • Watch for foraging ants (ants looking for food). Edges of bodies of water, trash cans and areas with spilled food or sugary drinks become areas where large numbers of foraging workers congregate.
  • Sometimes fire ants invade indoors. This is particularly common when conditions outdoors become very hot and dry or when flooding occurs in the immediate landscape.

For more information about fire ants and other stinging pest first aid, please visit the CDC website at

For more information about fire ant stings and how to treat them, read Fire Ant Stings on eXtension.

To learn more about treating anaphylactic shock and first aid in an emergency situation click here.

To learn more about fire ant lifecycles and biology click here.



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