United States Department of Agriculture

Animal and Plant Health Inspection Service

Program Aid No. 1996

Attention Baled 

Hay Producers— 

Don’t Transport 

Imported Fire Ants
The Threat

Imported fire ants (IFA) pose serious threats to people, 

young/newborn animals, crops, and agricultural equipment. 

These non-native pests often make their way into hay bales, 

which are then transported to other areas where new 

colonies can become established.

Recent drought conditions in many areas of the United 

States resulted in a great demand for hay, and bales from 

ant-infested areas were shipped to regions where the pests 

had previously not been present. As dry conditions continue 

in many parts of the country, the chances that IFA will again 

spread to new areas are great.

Fortunately, there are a number of practical ways to not only 

prevent initial infestations but also limit the spread of these 

harmful ants.

Description

Imported fire ants (Solenopsis invicta Buren, S. richteri Forel, 

and their hybrid) may look like ordinary ants, but they are far 

from ordinary. They are best distinguished by their aggressive 

behavior and mound-shaped nests.

These ants are 1/8 to 1/4-inch long and reddish-brown or 

black in color (fig.1). They live in colonies inside hard, moundshaped nests. While these colonies vary in size, a mature 

colony can grow to 300,000 ants. In addition, the mounds 

can get quite large, inhibiting field-worker activities and damaging farm equipment during times of cultivation and harvest.

IFA respond rapidly and aggressively when disturbed, clamping onto their victims with powerful jaws and stinging them 

repeatedly. Each sting injects a dose of venom that causes a 

burning sensation, earning these pests the name fire ants.
Figure 1. Imported fire ants are 1/8- to 1/4-inch 

long, and they are either reddish-brown or black.

Damage

IFA sting an estimated 14 million people each year in the 

United States. These stings produce itching blisters that can 

become infected. Although very uncommon, in severe cases, 

the stings can send sensitive victims into shock or cause 

death.

IFA often eat insects, but they will feed on almost any type of 

plant and animal material. These ants pose a direct danger 

to many plants, trees, and agricultural crops. They eat the 

buds of young trees and also feed on the germinating seeds 

of more than 125 native wildflowers and grasses.

The impact of IFA in Texas alone is estimated to be $1.2 

billion each year.
Figure 2. Most hay intended for shipment is 

stored in the field or in temporary holding areas.

Stopping the Spread

IFA were unintentionally introduced into the United States 

from South America almost 100 years ago. As of 2008, IFA 

infested more than 320 million acres in 13 States (Alabama, 

Arkansas, California, Florida, Georgia, Louisiana, Mississippi, 

New Mexico, North Carolina, Oklahoma, South Carolina, 

Tennessee, and Texas) and Puerto Rico. IFA commonly move 

to new, non-infested areas by hitchhiking on agricultural 

commodities, including baled hay.

The U.S. Department of Agriculture’s Animal and Plant Health 

Inspection Service (APHIS) works to prevent further IFA 

spread by enforcing a Federal quarantine and cooperating 

with IFA-infested States to regulate the movement of certain 

articles.

Regulated articles include: 

•	 baled hay and baled straw that are stored in direct

contact with the ground (fig.2); 

•	 soil;

•	 plants and sod with roots and soil attached that are

stored outdoors and intended for commercial sale; 

•	 used soil-moving equipment; and

•	 any other article or means of conveyance determined to

pose a risk of spreading IFA.
Hay from inside a quarantined area can be shipped anywhere 

else inside that quarantined area. However, hay from inside

the quarantined area is not permitted to move outside the 

quarantined area. 

APHIS has approved treatments for most regulated articles 

that kill fire ants and prevent new ant infestations. Once 

businesses have successfully treated their regulated items, 

APHIS will issue certificates/permits that allow the movement 

of those items to locations outside of quarantined areas.

Figure 3 depicts the most recent quarantine map. It is also 

located online at http://www.aphis.usda.gov/plant_health/ 

plant_pest_info/fireants/downloads/fireant.pdf.

To determine if a specific location is inside or outside the 

Federal quarantine, you can use APHIS’ online zip code 

locator at http://www.aphis.usda.gov/plant_health/ 

plant_pest_info/fireants/zipcode.shtml.

Figure 3. The most recent IFA quarantine map
Figure 4. IFA often nest adjacent to hay bales.

What You Can Do

Although there are many ways that IFA can get into hay bales, 

there is no single treatment method that can remove all IFA 

colonies in the hay while also making sure that the bales can’t 

become re-infested. 

However, there are several ways to manage these ants 

successfully in hay production systems. By following these 

best management practices, you can reduce the risk that 

your hay bales will become infested and keep IFA from 

spreading to new areas.

•	 Check your hay before you ship to see if it contains any

fire ants (fig.4). Attract the ants by putting an attractive 

food source (i.e., a dab of peanut butter or a piece of 

sausage) on the hay for an hour, and then check for 

ants (fig.5). This is best done when the temperature is 

between 65 and 90 °F.

•	 Elevate the bales several inches off the ground by

placing them on tires or pallets (fig.6). This will 

discourage ant colonies from moving into hay bales.

•	 Use broadcast bait applications of approved insecticides

around your hay storage area (fig. 7). A list of these 

products is available on the Texas Imported Fire Ant 

Research and Management Project Web site at http://

fireant.tamu.edu/broadcastbait/products/latest_greatest/pdf/latest_greatest_en_090507.pdf.

•	 Before loading hay bales onto trucks for transport to

non-quarantined areas, use high-pressure hoses to wash 

away IFA nests and any soil debris from support tires, 

wood pallets, and other shipping materials.
Figure 5. IFA frequently use hay bales as a 

source of food and refuge. IFA were discovered 

inside this bale by soaking a card in peanut oil 

and placing it on the bale.

Figure 7. IFA bait can be broadcast in and around the hay storage 

sites to significantly reduce IFA populations.

There are also a number of helpful practices hay buyers can 

follow to help reduce new IFA infestations:

•	 Ask if the hay you buy contains ants, and visually inspect

the hay bales when they are delivered to you. If possible, 

request that the hay be certified for movement by the 

State from which it is shipped. 

•	 Monitor for IFA in areas where hay bales are located and

continue monitoring throughout the period that the bales 

remain onsite.

•	 If you find any ants, correctly identify them. If you need

assistance, contact your State or local cooperative 

extension office. Contact information for Cooperative 

Extension System offices is available online at http://

www.csrees.usda.gov/Extension/index.html.

Figure 6. Keeping 

harvested hay from 

directly touching the 

ground is a good 

way to prevent IFA 

from entering the 

bales.
Using Insecticides 

Safely

General Sanitation

Because hay can become contaminated during IFA treatments, 

it is important to use care when applying insecticides close 

to hay bales. A two-step treatment regimen is the safest and 

most effective way to control fire ants.

Step 1 controls approximately 90 percent of IFA colonies in 

the general vicinity of the hay/straw bales. 

•	 Treat heavily infested areas or potential holding areas

using fire ant bait products that are registered with the 

U.S. Environmental Protection Agency for the site where 

the hay bales are located. Conventional bait formulas 

contain hydramethylnon, fenoxycarb, indoxycarb, 

pyriproxifen or s-methoprene. Apply the bait as a broadcast treatment according to the label instructions once 

or twice each year in an area extending out 1/2 to 1 

acre from where hay bales will be stored (fig. 7). 

Complete these treatments 1 month prior to moving 

bales into the storage area.
Figure 8. Special care should be taken when using insecticides 

in close proximity to hay bales so that the bales do not become 

contaminated.

Step 2 quickly eliminates specific IFA colonies that pose 

an immediate hazard by applying contact insecticides to 

individual mounds.

•	 Apply contact insecticides 3 to 7 days after bait treatments to specific IFA mounds according to label instructions (fig. 8). These contact insecticides come in three 

forms—granules, liquids, or dusts. Active ingredients 

include chlorpyrifos, diazinon, carbaryl, permethrin, or 

other similar agents. 
Barrier Treatments

Contact insecticides applied either to the soil area under hay 

bales or to a strip surrounding the bales are effective barrier 

treatments, provided the insecticides don’t come in direct 

contact with the hay. APHIS recommends these 

treatments in addition to broadcast baits. Results from 

previous IFA treatments show that barrier treatments are 

more effective when used in conjunction with broadcast bait 

treatments.

•	 Apply fire ant bait (as in Step 1 of the General 

Sanitation section above) prior to the placement of hay.

•	 Use strip applications to create a barrier surrounding hay

bales by applying contact insecticides approximately one 

yard around hay bales. Do not allow insecticide to drift 

onto hay bales.

•	 If using an area application approach, apply the barrier

contact insecticide to that location prior to placing the 

hay bales there. 

•	 Always use an untreated support pallet, tire, or landscape cloth (fig. 9) to avoid directly exposing the hay to 

chemicals.

•	 It is best to wait 24 to 48 hours after applying contact

insecticide before placing bales in a specific spot.

For soil treatments, research shows that using full label 

rates of liquid permethrin as a follow-up method to broadcast 

bait applications is effective for up to 5 weeks at deterring 

IFA from foraging and establishing colonies in hay bales. 

Permethrin also effectively kills IFA colonies when used to 

drench individual mounds.

However, permethrin should be used with caution, as it is 

toxic to livestock if applied directly to the hay that they will 

eat.
Figure 9. Keeping a barrier between the ground and the hay will 

help prevent IFA from entering the bales and protect the bales from 

contaimination by contact insecticides—thus reducing the likelihood 

that these pests will be transported to a new area during shipment.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs 

and activities on the basis of race, color, national origin, age, disability, and where 

applicable, sex, marital status, familial status, parental status, religion, sexual 

orientation, genetic information, political beliefs, reprisal, or because all or part of an 

individual’s income is derived from any public assistance program. (Not all prohibited 

bases apply to all programs.) Persons with disabilities who require alternative means 

for communication of program information (Braille, large print, audiotape, etc.) should 

contact USDA’s TARGET Center at (202) 720–2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250–9410, or call (800) 795–3272 (voice) 

or (202) 720–6382 (TDD). USDA is an equal opportunity provider and employer.

This publication reports research involving pesticides. All uses of pesticides must 

be registered by appropriate State and/or Federal agencies before they can be 

recommended.

___________________________________________________

CAUTION: Pesticides can be injurious to humans, domestic animals, desirable plants, 

and fish or other wildlife--if they are not handled or applied properly. Use all pesticides 

selectively and carefully. Follow recommended practices for the disposal of surplus 

pesticides and pesticide containers.

Issued February 2009

Additional Information

For more information on IFA and associated Federal restrictions, 

you should contact:

•	 your county agricultural extension agent

(go to www.csrees.usda.gov/extensions/index.html 

or check the county government section of your telephone 

directory under Cooperative Extension Service); 

•	 your State regulatory officials (go to www.statelocalgov.

net/50states-agriculture.cfm or check the State government 

section of your telephone directory under Department of 

Agriculture or Plant Protection); or 

•	 a Federal regulatory official in your State (go to

www.aphis.usda.gov/services/report_pest_disease/ 

report_pest_disease.shtml or check the Federal Government 

section of your telephone directory under U.S. Department of 

Agriculture, Animal and Plant Health Inspection Service, 

or Plant Protection and Quarantine). 

APHIS’ imported fire ant Web page, http://www.aphis.usda.gov/

plant_health/plant_pest_info/fireants/index.shtml, also offers 

a wealth of helpful resources, including pest alerts, brochures, 

quarantine maps, and Federal regulations.

The Texas Imported Fire Ant Research and Management Project 

is another useful source of information on IFA. The project’s 

Web site, hosted by Texas A&M University, is located at 

http://fireant.tamu.edu/.