The red imported fire ant, Solenopsis invicta Buren, is an introduced species that arrived in Mobile, Alabama from South America around the 1920s. This species has had an enormous impact in the southeastern United States, and continues to spread into areas of North America with mild climates and adequate moisture and food. Approximately 270 million acres in the southeastern United States and California are currently infested. A second exotic species, the black imported fire ant, Solenopsis richteri Forel, and hybrids between S. invicta and S. richteri occur in northern Alabama, Georgia, Mississippi and Tennessee, but not farther west.
Imported fire ants, hereafter referred to as fire ants, impact agriculture in a number of ways. They form tall, hardened mounds in clay-type soil that can damage field working equipment and slow down operations. Ants defending mounds can sting and cause medical problems for field workers. The ants have an affinity for electrical units, utility housings and structures, where they can cause equipment failures. Worker ants feed on some seeds and seedlings (sorghum, corn, small grains, forages, etc.) causing stand failure.
Fire ants prey on a number of other insects and arthropods, including boll weevils, many species of caterpillars, flea larvae, ticks, and chigger and prey upon beneficial insects like green lacewing larvae. They will also "tend" some species of sucking insects (aphids, mealybugs) which provide them with a sugary solution (honeydew) upon contact. These imported species have displaced many native ant species and eliminated food used by some wildlife. Fire ants can affect newborn livestock and wildlife, especially those animals on the ground or those nesting in low trees. Their stings can cause medical problems or even death to some animals with multiple stings. Although the research is not conclusive, populations of some wildlife species may be dramatically reduced.
Like other ants, the fire ant is a social insect and colonies reside in mounds of dirt that may exceed 18 inches in height. Fire ant mounds commonly occur in open, sunny areas. Periodically, winged reproductive male and female ants leave colonies on mating flights. Mated females (queens) can fly or be carried by winds for miles, land and start new colonies. Development from egg to adult occurs in about 30 days, progressing though four larval stages and a pupal stage. Worker ants (sterile female ants capable of stinging) can number in the hundreds of thousands in a mature colony.
Two forms of fire ants occur: single queen (monogyne) and multiple queen (polygyne) colonies. Areas infested by the single queen form may have 40 to 80 colonies per acre. Multiple queen colony infested land can harbor 200 to 800 or more ant mounds per acre. Worker ants from multiple queen colonies are not territorial and move freely from mound to mound. The opposite is true of workers from single queen colonies. Fire ant mounds can rapidly increase in number after agricultural lands are disturbed by mechanical operations or pesticide use. Due to the fire ants’ ability to form a mass of floating bodies, flooding can temporarily move fire ants out of flood prone areas and into areas that were not previously infested.
The fire ant disperse naturally through mating flights, mass movement of colonies or by floating to new locations in flood water. Fire ants can travel long distances when newly-mated queens land in cars, trucks or trains. Shipments of hay, nursery stock or soil from an infested area may relocate entire colonies or nests (see Quarantine Regulations).
Because fire ants are easily transported in nursery stock and soil, the United States Department of Agriculture (USDA) developed a quarantine program for this pest in the 1950s. This quarantine is designed to minimize the spread of the fire ant by requiring proper treatment and inspection of all nursery stock, turfgrass, hay and other articles shipped out of quarantined counties. Contact your state’s Department of Agriculture for specific information regarding compliance with these quarantine regulations.
This bulletin provides site-specific, goal-oriented management programs for agricultural situations where fire ant problems occur. You should select programs that use, where applicable, a combination of non-chemical and chemical methods that are effective, economical and least harmful to the environment. The goal of fire ant management is to prevent or reduce problems caused by unacceptably high numbers of fire ants.
Every effort should be made to direct control efforts only at the fire ant. Preservation and encouragement of competitor native ant species is thought to be the best long-term solution, since these species can reduce fire ant population densities by competing with them for food and resources, as well as control other pests.
Integrated Pest Management (IPM) is a concept used in many areas of agriculture to help producers determine if the cost of pest control can be offset by production gains before treatments are applied. The first step in any IPM program is to find out if, how often, and where losses occur and how much those losses actually cost. It is up to the individual to decide what “counts” as a fire ant-related loss and to put a value on that loss. If there is some question, it is often a good idea to make two assessments: one for definite losses and one for losses that might be attributable to fire ants. This method provides a range within which treatment expenditures can be adjusted.
In theory, management efforts should be implemented only where the monetary loss caused by a certain level of a fire ant population density equals or exceeds the cost for controlling them. This is the Economic Injury Level (EIL). The Economic Threshold (ET) is the level set below the EIL at which action is justified to prevent economic losses from occurring. Losses caused by the fire ant, however, are erratic and unpredictable. Loss estimates are best made from historical accounts on a given property.
Fire ant problems in livestock production systems are widespread and costly, but vary tremendously from ranch to ranch, even within the same locality. As a result, no “one size fits all” management plan can, or should, be used. More information on this topic is found in Managing Imported Fire Ants in Livestock Production Systems, Losses must be determined on an individual operation basis (see the worksheets at the end of this article or the Livestock Production article) and treatment plans tailored to minimize those losses at an acceptable cost.
In animal feeding stations, barns and feedlots, fire ants can cause problems similar to those found in poultry houses. Therefore, the programs for poultry houses (see below) can be adapted to treat fire ants in livestock barns and holding pens, provided products used are labeled for treating animal premises. Around barns and other structures use the Two-Step Method, provided the treated areas are inaccessible to animals and registered products are used. Conventionally-formulated bait products, such as Abamectin (Clinch®), hydramethylnon (Amdro® Pro), or pyriproxifen (Esteem®) can be broadcast-applied outside livestock pens according to directions. S-methoprene (Extinguish®) bait can be used in pens with no withdrawal or grazing restrictions.
Fire ants can cause problems on poultry farms by attacking chickens and foraging on broken eggs. Fire ant stings cause blemishes that can reduce the quality of poultry.
Program 1: For poultry houses and egg farms (use a combination of the following suggestions)
Program 2: Broiler houses
Program 1 for egg farms can be adapted to broiler houses, provided the products used are registered for this site. Because the broilers roam freely in the houses, care must be taken to avoid contact of chickens with insecticides by confining treatments to the outside of the broiler house (see Step 5 above).
Program 3: Free Range Chickens
Use bait stations on grid pattern
In cotton and sugarcane production, the fire ant is considered beneficial insects and no fire ant control is suggested. In cotton fields, fire ants are effective predators of caterpillars and can be sampled using the beat bucket method whereby the terminals of cotton plants are beaten into a plastic bucket to dislodge insects. In Louisiana sugarcane fields, habitat modification studies have been shown to increase fire ant abundance and predation by the ants on sugarcane borers, Diatrea saccharalis (Fabricius). There, control of fire ants increases the incidence of sugarcane borers and damage they cause; increasing pesticide use which counteracts the IPM program.
Fire ants occasionally feed on germinating seeds and seedlings of corn, sorghum and other field or cover crops, particularly during dry conditions in the spring, sometimes causing stand loss. Fire ants also have been reported to feed on young watermelon, cucumber and sunflower plants, and have damaged peanut and soybean plantings. Okra growers are constantly battling fire ants due to the ants’ attraction to the oils in the plant, nectaries, buds and developing fruit. Fire ant mounds can cause problems in areas where soybeans are not planted on raised beds or rows (i.e., they are flat-planted). The tall mounds along the rows interfere with harvesting equipment. During dry periods, the fire ants can chew irrigation tubing, as has been reported in vegetable crops.
The Imported Fire Ant Program Manual describes treatment programs for complying with the United States Department of Agriculture imported fire ant quarantine regulations. A separate publication lists quarantine treatments.
Federal quarantine regulations mandate specific fire ant treatment(s) for plants to be shipped to areas free of fire ants. Among fire ant infested states, there are different regulations and agencies that enforce them. In Texas and Louisiana, for instance, Floral and Nursery Laws mandate that plants must be apparently pest-free, but do not mandate formal treatment programs. In addition to those products mentioned below, other products, including those containing acephate (Orthene®), carbaryl (Sevin®), diazinon ant mound treatments, and abamectin (PT®370 Ascend®) and pyriproxyfen (Distance®) and s-methoprene (Extinguish® Professional Fire Ant Bait) conventionally-formulated baits, are also registered for treating fire ants in turfgrass areas, around ornamental plants or in potting media. However, these are not approved quarantine treatments at this time. The following treatment suggestions are for commercially produced ornamental plants to be shipped out of a quarantined area (modified from "Imported Fire Ants: A guide for Nursery Operators," Program Aid No. 1420, USDA, APHIS, December 1988). In all cases, the producer must obtain a Compliance Agreement from their state’s regulatory agency (i.e., Texas or Louisiana Department of Agriculture, Arkansas State Plant Board, Alabama Department of Agriculture and Industries). Greenhouse-produced plants may be exempt from quarantine treatment regulations if the facilities are determined to be tightly closed by the nursery inspector, although they still must have a Compliance Agreement.
Treatment options (for compliance with the USDA Fire Ant Quarantine):
Program 1: Fire Ant-Free Nursery Program for containerized nursery stock.
Program 2: For balled and burlapped stock.
1. Immerse stock in chlorpyrifos (Dursban® 4E), or drench stock twice daily for 3 consecutive days.
Program 3: For field-grown woody ornamentals, preharvest.
Note: Following treatment, nursery stock or plants must be shipped within a specific period of time, depending on the treatment applied.
Bodies of water, such as rivers, streams, ponds and lakes, are highly attractive to fire ants. Around fish farms and production aquaculture, fire ant mounds around ponds and on dams and levees can be a nuisance and pose a threat to workers. When using insecticides around these areas, every effort must be made to avoid contamination of water sources with fire ant control products. Fire ant bait products contain very small amounts of active ingredients and can be applied close to shorelines, avoiding direct application to the water. Risk of runoff into waterways is minimized when baits are applied during times of active ant foraging so that ants collect the bait particles quickly. Individual mound treatments should be made with care, selecting products with lower toxicity to fish, such as acephate (Orthene® TT&O). Pyrethrins and rotenone products should be avoided because of their high toxicity to fish. Do not apply surface treatments, baits or individual mound treatments if rains are likely to occur soon after treatment. Alternative non-chemical treatments, such as use of steam or very hot water mound treatments, may also be suitable for sensitive areas.
Fire ants invade bee hives and feed on developing bee larvae, occasionally destroying weak colonies. Use chemicals with care because the bees will be affected by insecticides.
1. Treat areas around hives using the Two–Step Method (see Cattle Production Systems, Pastureland and rangeland section) using products registered for the site in which hives are located. Conventional bait formulations (e.g., those containg hydramethylnon, pyriproxifen, or s-methoprene) are the safest for use around bee hives; dust formulations should be avoided.
2. Elevate the hives several inches on bricks or stones.
3. (Optional). The outer surface of the stand elevating hives can be carefully treated with a surface application of a non-volatile, long-residual contact insecticide. Specialty paint-on or paint additive formulations containing diazinon or chlorpyrifos (e.g., Insecta® Clear Finish, Killmaster® II) are available to produce a chemical barrier on surfaces. A registered contact insecticide also can be applied to the ground around the hives. Apply insecticides late in the evening or early in the morning when bees are not active to prevent bees from contacting treated surfaces. Read product labels and use insecticides and formulations least toxic to bees.
Certain forms of wildlife are especially affected by ants during and soon after birth or hatching. The risk is greatest during warm months. Fawns are vulnerable because they are born in June and because they instinctively remain motionless in their hiding places. Hatching quail and ground-nesting waterfowl chicks are also attacked. However, the impact of fire ants on area-wide populations of wildlife remains undocumented. Fire ant control programs in wildlife areas are discouraged unless the benefits from such treatments have been documented. Many pesticides are toxic to non-target organisms (particularly to aquatic organisms) and may directly or indirectly affect game species if not used properly.
1. Wildlife breeding areas are considered non-agricultural lands, and thus can be treated with products registered for this kind of site using the Two–Step Method.
2. Exotic game ranches are considered commercial agriculture areas. Breeding areas may be treated with products registered to treat livestock grazing areas or pastures using the Two-Step Method.
A number of ant species are native to the areas infested with red and black imported fire ant, including several other species of fire ants. Many of these ants compete for resources with the imported fire ants, attack mated queen ants trying to establish new colonies, and invade weakened fire ant colonies. Preservation and encouragement of native ant species is considered the best defense against the invasion of fire ants. In areas with less than 20 imported fire ant mounds per acre and where native ants are a concern, the broadcast application of a bait-formulated insecticide product is discouraged.
For additional information, contact your local County Extension Agent, entomology specialist or visit Imported Fire Ant eXtension or the Texas Imported Fire Ant Research and Management Project.
The information given herein is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by the participating states’ Cooperative Extension Service agencies in this regional publication is implied.
The authors are grateful to the thorough review comments from our colleagues in the Ant Pests eXtension Community of Practice..
ARE FIRE ANTS COSTING YOUR AGRICULTURE OPERATION MONEY?
WORKSHEET I: Livestock
How many acres are in your agriculture operation ................................................. _______
1. How much do you spend in an average year to treat injured animals?
Include medicines, bandages, vet bills and an estimated cost of your time ... $_______
2. A. How many animals do you lose per year to ants? If less than one, give a fraction (e.g., 1 calf/2 years = 0.5 calf/year). Include only those directly killed by ants ............................... ______
B. What did you pay for the young or value added to adult animal? .................................................$______
C. How much profit if calf had been sold normally? ......................................................$______
Add B and C, then multiply by A to get total death losses ....................... $_______
3. What are your average yearly losses due to fire ants for the following:
Cost of material + labor including your own = Total
Ruined Feed $______________+$__________ = $__________
Ruined Hay $______________+$__________ = $__________
Shredder damage $______________+$__________ = $__________
Electrical damage $______________+$__________ = $__________
Other damage/loss $______________+$__________ = $__________
Add the above items to get Total material and equipment losses .... $__________
4. Losses in Hay Production, from other form if applicable ................................. $__________
5. Any Medical Costs for you, your family, or workers per year ................................ $__________
6. Per year losses to other animals i.e., pets, horses, food animals, exotic breeds, if not covered in #2..................... $__________
7. Any other per year losses that can be blamed on fire ants ................................ $__________
GRAND TOTAL. Add totals for 1-7 ............................................................................ $__________
CAN YOU AFFORD TO TREAT FOR FIRE ANTS?
Grand Total ÷ number of acres in your operation = $_____________ per acre in losses.
If your LOSS PER ACRE is:
! Greater than about $12, you can probably make money by treating your entire place.
! Less than about $12, you need to pinpoint where these losses occur and only treat those areas.
Texas A&M AgriLife Extension Service
Paul R. Nester, Extension Program Specialist,
Robert T. Puckett, Assistant Professor and Extension Entomologist
Auburn University and the Alabama Cooperative Extension System
Kathy Flanders, Extension Entomologist and Professor,
Kelly Palmer, Animal Sciences and Forages Regional Extension Agent
Fudd Graham, Research Fellow IV
University of Georgia and the University of Georgia Cooperative Extension Service
Dan Suiter, Professor
Tim Davis, Ph.D., Chatham County Extenson Coordinator
University of Arkansas System, Division of Agriculture, Cooperative Extension Service
John Hopkins, Associate Professor and Extension Entomologist
Kelly Loftin, Extension Entomologist
Louisiana State University AgCenter
Dennis Ring, Entomologist, Extension Specialist, Professor
This publication was originally written and published as:
Drees, B. M., C. L. Barr, D. R. Shanklin, D. K. Pollet, K. Flanders, and B. Sparks. 1998. Managing red imported fire ants in agriculture. B-6076. Texas Imported Fire Ant Research & Management Plan. Texas A&M University, College Station, Texas. 18 pp