Fire Ants – An Integrated Pest Management Overview

Although there are several fire ant species in the United States, the main pest ant species is the red imported fire ant. Scientific name: Solenopsis invicta. The red imported fire ant, commonly referred to as RIFA, is native to tropical areas of South America. It was brought to the southern United States between the 1930s and 1940s and has since established itself as a formidable pest in the southern areas of the United States.

The red imported fire ant is also found in the Caribbean, and parts of Asia and Australia. Aside from their painful sting, red imported fire ants displace native ant species and cause approximately $7 billion in annual losses in the United States.

Fire Ant Identification

• Size: 1/8 to 1/4 inch
• Color: Dark reddish-brown
• Two visible nodes on the petiole (area between the thorax and the abdomen)
• Antennae has 10 segments

The trademark of the red imported fire ant is the ant mounds. More specifically the fire ant’s reaction when their mound is disturbed. Fire ants aggressively and ferociously defend their nest against your invading foot or picnic blanket. When threatened, fire ants attach themselves to you with their strong jaws and repeatedly inject their venom with the stinger on their abdomen.

These painful stings result in a white, bump-like pustule. RIFA mounds are usually less than 18” in diameter and tend to be outdoors in landscaped or manicured areas. They may also be under patio slabs and at the edge of the pavement or concrete. Red imported fire ants may nest in outdoor electrical equipment and in certain conditions, they may also build nests inside wall voids and air conditioning units.

Fire ants are omnivorous meaning they eat both meat and plants. In nature, fire ants eat honeydew and other sweets, as well as earthworms and other insects. When baiting for fire ants, a key component to success is attracting them with an enticing mixture of sweets, proteins, and fats.

Red imported fire ants are often confused with the native fire ant, Solenopsis geminate Fabricius, however, the sting of this species does not result in a pustule and they are much less common. Pyramid ants (Dorymyrmex spp.) often build mounds in the same areas as fire ants and may be confused with fire ants. However, pyramid ants do not sting and are actually predators of fire ant swarmers. Many people automatically assume any red or dark brown ant they encounter is a fire ant, however, once you positively identify the red imported fire ant in your yard, steps to control these pests should be implemented.

Where Do Fire Ants Live?

Fire ants live in colonies with hundreds of thousands of ants. They build mounds from soil that cover a vast underground network of tunnels. These tunnels house and protect the fire ants in the colony, including the queen, and may extend 25 feet into the ground. Some fire ant colonies only have one queen, but most fire ant colonies are polygyne, meaning they have more than one queen.

The primary method that a well-established fire ant colony expands is through a mating flight. On a warm sunny day after a rain in the spring and fall, as many as 4,500 winged fire ants (alates) fly from the nest. They mate during this nuptial flight; the males die and the females search for a place to bury themselves and lay their eggs.

Fire ants reproductives are attracted to pools for some reason, and often a homeowner will wake up to find thousands of winged alates on the surface of the water. This nuptial flight can occur as many as 6-8 times per year. Through this process, in the southern states, a fire ant-infested acre may have as many as 97,000 active fire ant queens on it.

Fire ants are primarily an outdoor pest, building mounds in athletic fields, outdoor grassy areas, patios, and the edges of pavement, but they forage for food and sometimes end up indoors. Anything parked or placed directly on grass, such as busses, recreational vehicles, or portable classrooms, is at higher risk of foraging fire ants entering the premises.

Pay special attention in areas where food is either prepared or served and areas where people are in close contact with the ground, such as playgrounds and athletic fields. In extreme heat or flood, fire ants may move indoors, but the best indoor control for fire ants is to control them outside.

Fire Ant Bites

A fire ant attack can turn an afternoon of outdoor fun into an unpleasant reminder of the ferocity of nature. When a fire ant mound is disturbed, fire ants quickly descend upon your feet ankles, and legs and hold on tight. Fire ants actually bite and sting, but it is the sting that leaves the pain and the pustule. The worker ants hold on tight to your skin with its jaws; they use this “anchor” to propel the stinger on their rear end into your body injecting you with the venom. Fire ants can sting their victims, multiple times often in a circle rotating around the “anchor” of the bite.

The venom of the red imported fire ant causes pain, redness, itchiness, and a pus-filled blister at the site of the sting. The most severe reactions to fire ants are because the victim is allergic to the venom.

If an allergy is present, symptoms may include to following:

• Dizziness
• Nausea
• Difficulty Breathing
• Swelling of Throat or Tongue
• Low Blood Pressure
• Loss of Consciousness
• Even death

If you experience of any these symptoms after being stung by fire ants seek medical attention immediately.

Unless they are having a severe reaction as described above, most healthy adults do not need medical treatment after a fire ant episode. However, simple home remedies can provide some relief from itching and burning.

• A cold compress can help alleviate the swelling.
• Hydrocortisone cream can help alleviate itching.
• Antibiotic ointment can help prevent infection from pustules that have opened.

Curious pets running through grassy fields are likely to encounter fire ants. When your pet’s paw disturbs the fire ants, he too will get stung and injected with their venom. The first and most important thing to do is make sure you swat all the fire ants off your pet’s body, especially in hard-to-reach places such as between his toes. It is a good idea to put glove on to protect your own hands before removing the fire ants from your pet.

Monitor your pet for any systemic or allergic reaction. If you notice any sign of respiratory distress, vomiting, or weakness, call your veterinarian immediately. If your dog is especially sensitive to fire ant stings do not hesitate to call your veterinarian. They may prescribe steroids for the swelling and itching and an antibiotic to prevent infection.

How to Treat & Control Fire Ants

Integrated Pest Management (IPM) practices can be successfully utilized to combat fire ants. IPM focuses on pest prevention, sanitation and monitoring, physical and mechanical treatments, and applying reduced exposure treatments to areas of pest activity. By actively engaging with your landscape, noticing a fire ant mound as soon as it presents itself, and monitoring the results of any treatment you apply, you can get rid of fire ants using IPM principles.

Preventing Fire Ants by Inspection, Sanitation, and Monitoring

Specifically, in areas of the south, where fire ants are known to populate, preventative fire ant measures should be in place. In areas where people, specifically children, are known to congregate, such as schools, ball fields, restaurants, and play-grounds regular fire ant inspections should occur. However, when you find a fire ant mound, it is best not to disturb it. Your bait treatment will be more effective if the fire ants are undisturbed.

Focus your inspection on fire ant vulnerable areas such as the following:

• Grassy areas, specifically athletic fields, edges of concrete, and playgrounds
• Food preparation and serving areas, such as commercial kitchens, classrooms where snacks are consumed, hospital or ALF rooms where food may be consumed in beds
• In and around buildings look for signs of fire ants and potential building entry points
  • Check all windows and doors for tight seals.
  • Check flat roofs and gutters for mounds in leaf litter and possible entry points.
  • Check electrical equipment for nests and damage

If you locate just one fire ant mound during your inspection, that is sufficient to justify fire ant treatment.

In areas with a past history of fire ants, and high foot traffic, or areas where multiple mounds are located close together, a broadcast bait application may be necessary.

Especially in commercial spaces, where liability may become an issue, documentation of your fire ant inspections and any treatment performed becomes significant. In an effort to minimize pesticide use and reduce costs, we encourage homeowners to also keep track of the number and location of fire ant mounds in your yard. Document your treatment efforts, then monitor the success of your efforts.

Fire Ant Monitoring Program

As expected, visually searching for fire ants is the most common method of monitoring, but sometimes more is needed. If fire ant foragers are entering your home but you can not find the mound, you can narrow down your search area by using food lures. Food lures are also useful where the fire ant mound is inaccessible, and you need to know if the colony has been eliminated by your treatment.

To monitor for fire ants using lures, place potato chips, hot dog slices, or tuna fish chunks every 10-20 feet in the area to be monitored. These lures will be most effective if the temperature is between 65℉ and 95℉. After about 30 minutes to an hour check your food lures. Fire ants are voracious eaters and will find the lures if they are in the area. Properly identify and count the ants to locate fire ant colonies and measure the success of any treatments you have applied.

Preventing Fire Ants by Sanitation Efforts

Good sanitation practices are paramount to keeping your home or business pest free. Proper sanitation and food storage can help prevent fire ants from foraging, or wandering, into your home in search of a meal, but it will never eliminate the fire ants in your yard.

Like most ants, fire ant foragers leave a pheromone trail from their nest to the food source. Regular cleaning of surfaces particularly where you’ve seen fire ants trailing, will disrupt this pheromone trail and make it harder for them to find your food again. Wash all dishes promptly and clean surfaces on a regular basis.

• Quickly clean up grease and spills
• Store food items in sealed plastic containers or bags or in the refrigerator, and keep outside of containers free of residues
• Ensure that recycling is rinsed and relocated to outdoors recycling containers as soon as possible
• Use liners for trash receptacles and empty at the end of the day so that food is not left in the building overnight.
• Control honeydew-producing insects on plants, such as aphids, scales, mealybugs, and whiteflies.

Potential water sources

• Preventing access to water by fixing plumbing leaks (including irrigation around the building) and repairing damp wood
• Improving drainage to reduce humidity and moisture around building, including diverting AC condensate lines

Potential harborages

• Modify the outdoor habitat to reduce ant contact with the building and increase ease of inspection for ant trails by:
  • Preventing access to electrical equipment
  • Trimming vegetation that is touching buildings
  • Remove fallen branches and rocks from around the building
  • Clearing mulch that is contacting foundations. Rake 12” from building leaving a layer that’s thin enough to dry out naturally (1 inch thick)
  • Move trash cans or dumpsters away from building entryways.

Physical and Mechanical Fire Ant Treatments

If your fire ant inspection reveals fire ant mounds, or despite your sanitation efforts, fire ants are still trailing into your home, it is time to go to the next level of fire ant control. Before you utilize pesticides, physically manipulate the environment to either remove or block out any pests including fire ants.

• Remove ants using a HEPA vacuum or wipe/wash away.
• If ants are observed foraging in the building it is necessary to identify the site of entry. Eliminate the access point where ants are entering by:
  • Sealing cracks and crevices with caulk or expandable foam especially plumbing and utility penetrations
  • Installing door sweeps
  • Repairing door and window seals

Fire Ant Treatments

Due to the public health risk associated with fire ants, chemical options, such as baits and insect growth regulators (IGRs), can be used on a routine or calendar-based schedule. However, this should only be done in regions of the country where fire ants pose a potential issue. In Florida and other southern states, due to the high levels of fire ant activity, consider baiting for fire ants on a quarterly basis, or every 3 months.

Always read and follow the label. The label is the law. Pesticides must be used in accordance with federal, state and local regulations. Applicators must have proper credentialing to apply pesticides and should always wear personal protective equipment (PPE) as required by the pesticide label during applications. All labels and Safety Data Sheets (SDS) for the pesticide products authorized for use in the IPM program should be maintained on file.

The preferred chemical management option for fire ants is an insecticide bait.

Fire ant baits are the most effective treatments available and are also low risk treatments that reduce the potential for insecticide exposure to children and pets. Fire ant baits contain both and food-based attractant and a chemical active ingredient. When consumed, the active ingredient acts upon the fire ants and causes their death.

Because of the foraging behavior of ants, baits are more effective because they kill the ants deep within the nest. Just as ants will carry back potato chips or hot dog buns back to the nest to feed the colony, the foragers also carry the bait back to the nest. The bait is the then fed to all the ants, including the queen, and the entire colony is eliminated.

Remember, parts of the nest can be up to 25 feet down. Sprays will not penetrate that deep. When using baits, the fire ants do the hard work for you and move the bait throughout the entire colony.

• Fire ant baits are typically available as a corn-grit based granule that can be used as a spot treatment around existing mounds or broadcast over the entire property.
• The cost of a labeled bait application is often much less than an application of a liquid residual insecticide.
• Broadcasting baits may also reduce the overall amount of insecticide applied compared to residual liquid applications.
• Some modern baits work as quickly as liquid residual spray products. This eliminates the need to do mound drenches.

How to Choose the Best Fire Ant Killer

*Products listed are not endorsements, just examples.

Currently, there are numerous fire ant baits on the market to choose from. When choosing a fire ant bait, make your selection based upon:

• The time it takes to kill the fire ant colony
• Active ingredient (AI) classification
• Cost

Baits that also contain Insect Growth Regulators, or IGRs, as a second ingredient may help keep fire ant populations from rebounding as quickly. IGRs do not kill fire ants directly, rather they prevent fire ants from fully developing and reproducing. Baits containing only IGRs are available, but they may take several months to gain control.

• Baits such as Advion® Fire Ant Bait kill fire ants in as little as a few hours. These baits are great for doing an initial mound treatment to reduce the pest population quickly.
• Baits such as Amdro® and Extinguish® Plus contain slower acting active ingredients that can take up to a week to kill individuals. These baits are cheaper and are a good choice for quarterly preventative applications.
• For large areas where cost is a factor, a combination can also be used. For example, you can broadcast a less expensive slow-acting bait such as Extinguish Plus to the entire area and spot-treat mounds with a fast-acting bait such as Advion Fire Ant Bait.

Baits are most effective when fire ants are actively foraging; think good weather for a picnic, or temperatures are between 70 and 90°F. Fire ant baits become unpalatable within a few hours of getting wet. Don’t apply bait just before or after a rain; you must give the fire ants time to locate the bait and take it back to the nest. If possible, choose a day for your fire ant treatment when rain is not forecasted. Apply the fire ant bait after the morning dew has dried. Once again, think “Is it good weather for a picnic?”

When applying fire ant bait to a fire ant mound take care to not disturb the mounds. Carefully follow the label instructions; do not simply dump a large amount of bait on top of the mound. The ants will know this is unnatural and will deem the bait a threat to the colony. Fire ants will be more likely to “take the bait”, if they forage for it as they normally forage for their food.

Fire Ant Baits Marketed to the Homeowner

For the reasons stated above, the IPM preferred method of treatment for fire ants is baits. Many popular fire ant control products sold at big box stores are not baits. When selecting a fire ant product from your local store, be sure to check the label closely to ensure it is a bait and not a traditional insecticide.

Many products in big box stores have very similar names, Some are baits and some with similar names are not baits. Traditional spray mound treatments often do not kill the queen and eliminate the colony.

If you are reading this, you may have already chased fire ant mounds around your yard. The fire ant mound is simply the entry and exit to the underground nest. The actual fire act colony is deep underground, up to 25 feet underground. When disturbed by a mound treatment, fire ants will simply move the mound over 5 feet and proceed as usual. Baits rely on using the fire ants themselves to deliver the active ingredient deep within these tunnels to kill the entire colony.

When deciding upon which fire ant bait to purchase, be aware that between products sometimes the same active ingredient is used. However, one product may contain up to 10x the active ingredient. In addition, each bait relies upon food attractants to entice the fire ants to eat it and bring some back for the others. These attractants are proprietary to unique to the fire ant baits so side by side comparison is difficult. Ensure the fire ant bait is fresh. Just as we throw away bags of stale potato chips, fire ants are not likely to bring home stale bait.

Shopping for a fire ant treatment at your local big box store can be confusing. Many products are marketed under trade names and make big promises. When you are staring at the options in the aisle, it can be very easy to pick a product that is not a bait. However, if you know exactly what you are looking for, there are some good fire ant control options available to the homeowner.

For example, Ortho is a brand or tradename, and they market many different products under this name. Ortho does have a bait product; it is called ORTHO® FIRE ANT KILLER MOUND BAIT. This Ortho bait product utilizes the active ingredient Indoxacarb which can effectively kill fire ants in under 24 hours. However, ORTHO® ORTHENE® FIRE ANT KILLER uses Acephate, which is not a bait, as its active ingredient. Yet another Ortho product ORTHO® FIRE ANT KILLER BROADCAST GRANULES is meant to treat your entire lawn with Bifenthrin, which is not a bait, as its active ingredient. Take your time when choosing a bait and make sure to do your research before you head to the store.

Another area of confusion in homeowner fire ant control is centered around the easily available product Over ‘n Out®. This product used to be a homeowner version of the professional only fire ant killer Topchoice. These products were the only effective non-bait product for fire ants. They treated the soil for up to a year and while not being 100% effective, they reduced the chance of new fire any colonies drastically.

However, years ago the EPA listed the active ingredient Fipronil as a Restricted Use Product when used in landscapes due to the potential for groundwater contamnation. It is now only to be used by licensed pest control professionals. Instead of discontinuing the product, Over ‘n Out® changed the active ingredient to a less effective product. Over ‘n Out® now contains Zeta-Cypermethrin and Bifenthrin.

TopChoice is still available to licensed professionals. We do recommend TopChoice applications in addition to the use of baits for sensitive areas where even a single fire ant mound is unacceptable and dangerous. For example, athletic fields, school bus-stops, day cares, nursing homes, playgrounds, etc. are all commonly treated with TopChoice in addition to baits to reduce future fire ant colonies.

Natural or Homemade Fire Ant Remedies

The internet is filled with “natural remedies” for fire ant mounds. Homeowners have become aware of chemicals and pesticides used in and around their homes and often search for environmentally friendly ways to take care of their pest problems.

Natural fire ant suggestions include pouring boiling water or club soda on a fire ant mound, mixing fire ant colonies in the hopes they will fight and kill each other off, spreading grits near the mound so they expand and explode, diatomaceous earth, or using cinnamon, coffee grounds, or orange oil to repel fire ants. There is no evidence that these home remedies eliminate fire ant colonies. In fact, most have proven to be completely false.

Some of these suggestions may kill the few fire ants that they physically contact, but remember, the majority of the fire ants are located deep underground. The foraging ants you see on the surface is typically only about 10% of the colony. These home remedies will not kill the queen and the rest of the colony.

Integrated Pest Management Practices always seek to use the least amount and safest possible pesticides; hence our strong recommendation to use baits rather than mound treatments and broadcast applications for fire ant control. Baits are more effective against fire ants and use less pesticide, allowing for more environmentally friendly fire ant control.

Fire Ant Baiting Tips

Baiting takes advantage of the natural instincts fire ants. However, sometimes ants can be finicky eaters and just won’t “take the bait.” If your fire ants either are not eating the bait or have not yet died, troubleshoot with the fire ant bait tips below.

• Do not spray pesticides when using baits. Ants can smell the pesticide on the bait, and they will avoid the bait. Insecticide sprays also scatter the ant infestation, making it more difficult to place baits effectively.
• After setting out bait, observe to see if the target ant is taking the bait. Fire ants are aggressive foragers, typically you will see some carrying bait back to the colony within minutes.
• Is your bait old and rancid? This is the most common problem. Once you open a container of bait it goes bad quickly. It is similar to a bag of potato chips…. Would you eat an open bag of potato chips that has been sitting in your garage since last year? Even is so, fire ants will not. Always buy no more than you need so you apply fresh bait.
• Is your bait placement correct? When baiting for fire ants scatter bait 1-3 feet around the base of the mound. Do not dump bait on top of the mound.
• Don’t destroy the mound, or overly disturb it. Too much disturbance will encourage alarm pheromone production and nest movement, which will impact your treatment.
• Depending on their dietary needs at any given time, fire ants may prefer a protein bait or a sweet bait. If the fire ants are not consuming your protein-based bait, try offering them a sweet-based bait.

FAQ’s