DIY Fire Ant Control: A Comprehensive Guide for Homeowners

Fire ants are notorious for their aggressive behavior and painful stings, making them a significant concern for homeowners across many regions. Understanding why fire ants build mounds, the optimal time to treat them, and the best methods to use can help you regain control of your yard. In this comprehensive guide, we’ll delve into the behavior of fire ants, explain why they build mounds near slabs and patios, and offer a detailed list of chemicals that homeowners can use to kill fire ants effectively.

Understanding Fire Ant Behavior: Why Do They Build Mounds?

Fire ants (Solenopsis invicta) are social insects that form large colonies in underground nests. These nests, marked by the presence of mounds, serve several purposes for the fire ants, such as protection from predators and shelter from environmental conditions like flooding. A typical mound can house thousands or even hundreds of thousands of fire ants, including workers, brood (eggs, larvae, and pupae), and the queen.

But why do fire ants build mounds, and what makes them so prevalent in certain areas of your yard?

1. Protection and Survival

Fire ants construct their mounds primarily for protection. The above-ground portion of the mound acts as a shield against potential threats, whether those come from predators, weather conditions, or human interference. The nest below the mound is an intricate system of tunnels and chambers designed to house the colony, store food, and raise the brood.

2. Temperature Regulation

One of the most critical functions of the mound is to regulate the temperature of the nest. Fire ants are cold-blooded, meaning their activity is highly influenced by external temperatures. The mound helps maintain an ideal microenvironment by absorbing and releasing heat, allowing the colony to remain active during cooler months or in early mornings when the ground temperatures are lower.

3. Flood Prevention

Fire ants are adept at adapting to fluctuating environments. In areas prone to heavy rains or flooding, mounds provide a refuge where ants can escape rising water levels. The elevated structure of the mound ensures that the colony can survive even during adverse weather conditions.

Why Fire Ants Build Mounds Near Slabs, Patios, and Sidewalks

If you've noticed that fire ant mounds tend to appear near sidewalks, patios, or concrete slabs, you're not alone. This behavior is common and ties into the ants’ ability to seek warmth and protection.

1. Heat Sinks in Cooler Months

Concrete slabs, sidewalks, and patios act as heat sinks. These structures absorb heat during the day and slowly release it as the surrounding temperatures drop at night. Fire ants exploit this feature by building their nests near these heat sources, particularly in the fall and winter months when maintaining a stable, warm temperature for the colony becomes essential for survival.

The warmth from these areas extends to the soil beneath the slabs, creating an ideal microclimate for fire ants. This allows them to remain active and continue foraging even when surface temperatures would typically render them dormant.

2. Protection from Weather Extremes

Slabs and other solid structures also offer some degree of protection from environmental extremes. The nests built under or near these structures are less likely to flood during heavy rains or be disturbed by human activity. Additionally, the overhead cover provides a buffer from temperature fluctuations, further enhancing the ants’ ability to thrive year-round.

When Is the Best Time to Treat Fire Ant Mounds?

Timing is a critical factor in the successful control of fire ants. While they are a year-round problem in warmer regions, there are certain times when treatment is most effective.

1. Spring and Fall: Optimal Treatment Periods

Fire ant activity peaks during the spring and fall seasons, making these periods the most effective time to treat mounds. During these months, temperatures are mild enough for ants to forage actively. Treatments applied when ants are actively foraging will have a higher chance of being carried back to the colony, affecting a more significant portion of the population, including the queen.

Additionally, applying treatments in the fall is particularly important. As temperatures begin to drop, fire ants seek warmth and protection by retreating deeper into their mounds. Treating during this period can prevent colonies from surviving the winter months, reducing their numbers come spring.

2. Early Morning or Late Afternoon

If you're applying fire ant bait products, early morning or late afternoon are ideal times to distribute the bait. During these times, ants are most likely to be foraging for food, increasing the chances that they will collect the bait and bring it back to the colony for consumption.

How to Control Fire Ants: Treatment Methods and Chemicals

DIY fire ant control can be an effective way to manage small to moderate infestations. The two primary methods of fire ant control are baiting and mound treatments. Both approaches can be successful, but they work best when used in combination.

1. Fire Ant Baits

Baits are a preferred method for many homeowners because they work by targeting the entire colony, including the queen. Fire ant baits consist of insecticides mixed with a food attractant, which worker ants collect and bring back to the mound to share with the rest of the colony.

Some of the most effective fire ant baits include:

• Advion Fire Ant Bait: Contains the active ingredient Indoxacarb, which is highly effective at eliminating colonies by targeting both workers and queens.
• Amdro Fire Ant Bait: This bait contains hydramethylnon, which disrupts the ants' energy production, eventually killing the entire colony.
• Extinguish Plus Fire Ant Bait: A dual-action bait, this product combines hydramethylnon with an insect growth regulator (IGR) to prevent colony reproduction while eliminating active workers.

How to Apply Fire Ant Baits:

• Apply baits around the mound, not directly on top of it.
• Use a broadcast method to cover large areas, ensuring you reach ants that may not yet have built visible mounds.
• Ensure the soil is dry and avoid treating just before rain, as water can wash away or degrade the effectiveness of the bait.

2. Fire Ant Mound Treatments

Mound treatments are applied directly to the fire ant mound and are designed to kill ants on contact. These treatments can provide quick relief from active mounds but may not eliminate the entire colony unless the queen is killed.

Some effective fire ant mound treatments include:

• Ortho Orthene Fire Ant Killer: This product contains acephate, an insecticide that works on contact to eliminate the colony. It is a popular choice for its fast-acting results.
• Surrender Fire Ant Killer: Another acephate-based product, Surrender is known for its ability to quickly neutralize fire ant mounds and provide long-lasting control.
• Bayer Advanced Fire Ant Killer Dust: This product contains cyfluthrin and can be applied directly to the mound for fast results.

How to Apply Mound Treatments:

• Apply the product according to the label directions, generally by sprinkling it over the mound and watering it in.
• Treat mounds during cooler times of the day when ants are closer to the surface.
• Repeat treatments if the mound reappears after a few weeks, as some colonies may require more than one application.

3. Combination Treatments:

For maximum effectiveness, a combination of baits and mound treatments is often the best approach. Baits ensure that the entire colony is targeted, while mound treatments provide immediate relief from visible mounds.

List of Chemicals to Kill Fire Ants

Several chemical options are available to homeowners looking to control fire ants. Below is a list of the most commonly used and effective chemicals:

1. Indoxacarb (Advion Fire Ant Bait): Targets the entire colony, including the queen, and is highly effective.
2. Hydramethylnon (Amdro Fire Ant Bait, Extinguish Plus): Disrupts energy production in fire ants, killing them over time.
3. Acephate (Ortho Orthene, Surrender Fire Ant Killer): A fast-acting insecticide that works on contact, eliminating mounds quickly.
4. Cyfluthrin (Bayer Advanced Fire Ant Killer): A broad-spectrum insecticide that kills ants on contact.
5. Spinosad (Green Light Fire Ant Control): A natural insecticide derived from soil bacteria, spinosad works by disrupting the nervous system of ants.
6. Fipronil (Maxforce FC Fire Ant Bait): A slow-acting bait that allows workers to carry it back to the colony, ultimately killing the queen and the colony.

Controlling fire ants doesn’t have to be a daunting task for homeowners. By understanding why fire ants build mounds, especially near slabs and patios, and by applying treatments at the right time and with the right products, you can effectively reduce or eliminate fire ant colonies in your yard. Spring and fall are the most critical times to treat fire ants, and a combination of baits and mound treatments will provide the best results.

Be sure to follow all label directions when using chemical treatments, and remember that persistence is key. With the right approach and knowledge, you can keep your property fire-ant-free year-round.

Fire Ant MoundPhoto byD & D Pest Control Co. - Tom Davis