ALABAMA rCOOPERATIVE AExtension

S Y S T E M

CIRCULAR ANR-999

The Argentine ant, I.inepithemahumile (Mayr)-formerly namedIkkv7z~yrme.x one ofthe more troublesome ants inAlabama. Argentine ants are mainlya nuisance to people because theyare often found indoors, formingwide, noticeable lines or trails ofants into homes (Figure 1).

These ants do not sting or bite.They are 2-3 mm in length andblack to brown in color (Figure 2)Argentine ant workers are all aboutthe same size (monomorphic), incontrast to fire ants, where workerscan be different sizes (polymor-phic). Workers emit a faint mustyodor when crushed.

Colonies are large and can con-tain many queens. Nests can beidentified by the presence of brood.Brood are the larval and pupalstages of the ant. Brood are creamcolored to white and immobile, soworkers ants must carry them whenthey need to be moved.

These ants probably arrived inLouisiana in the 1870s on coffeeships from Brazil. They rapidlyspread throughout the United States.Entomologists have been trying tocontrol these ants since the early1900s. Argentine ants avoid the coldwinters by inhabiting heated build-ings.

Control Of Argentine Ants Argentine ants are difficult to

control for the following reasons.• All ants are holometabolous

(complete metamorphosis), havingan egg, larval, pupal, and adultstage. Foraging adult ants are only afraction of the total colony.Broadcast spraying around theperimeter of the house targets onlythe foraging adult ants in thecolony. Control will be temporarysince the colony will simply sendout more foraging ants when othersarc killed.

A L A B A M A A & M A N D A U B U R N U N I V E R S I T I E S

IPM Tactics For

Figure 1. Noticeable lines or trails of ants. Arrow denotesqueen relative to worker ants.

Figure 2. Argentine ants feeding on sugar source. Line depictsactual size of the ants.

• The colony supports multiplequeens if ant populations are large.If a broadcast spray around thehouse is the primary method ofcontrol, the Argentine ant workersand queens will scatter. When theants scatter in sufficient numbers,new colonies can be formed. Theone main colony can split into sev-eral smaller ones, all of which havethe potential to grow. Thus, broad-cast spraying alone can make theproblem worse.

•Unlike many other ant species,Argentine ants from differentcolonies do not fight. Therefore,their spread is less limited becausethey are not territorial.

• Even with theirlarge colony size theyare quite mobile andcan move from one areato another quickly. Abroadcast spray maytemporarily alleviate anArgentine ant infesta-tion. But there is a goodpossibility that the antswill simply move to an-other area until thechemical breaks down.After the chemicalbreaks clown, the antswill return because theyare constantly scoutingand foraging for food,water, and nesting sites.

• Heavy mulchagainst the walls ofhouses creates pocketsof moisture that theseants need.

• Potted plants are afavorite nesting site.Moving infested potsinto the house can cre-ate an indoor infestation.

These characteristicscombine to create a pestcontrol nightmare.Argentine ant controlin the Southeast is an

ongoing effort. Due to the largesize of the colonies and their rapidmobility, even if one colony is elim-inated, another will move into thearea over time.

CIPM Control ProgramAn Integrated Pest Management

(IPM) approach offers a greaterchance for control of the Argentineant, An IPM approach incorpomtesall available control methods into apest management program. IPMmethods include identification, in-spection, sanitation, exclusion, andchemical strategies.

IdentificationFor maximum control make sure

you properly identify the ant pest.Different ants have different foodpreferences and different behaviorsthat will directly impact the efficien-cy of ant pest control.

Collection Tip—One way tocollect ants for identification is toplace a dab of honey or sugar waterin the center of an index card. Placethe index card where ants are seen.Allow ants to recruit to the sugarsource. Put ants on the index cardinto a plastic bag, then place thebag in the freezer. The cold temper-atures will slow- the ants down orkill them. When they are immobi-lized, the ants can be easily tappedinto a vial of alcohol and submittedfor identification.

InspectionFind the source of the ants. Place

bait or granules where the ants areforaging or nesting. Generally,Argentine ant trails will be conspic-uous (Figure 1). If trails are not ob-vious, placing an index card with adab of honey or sugar water whereants have been seen may help lo-cate established trails as ants recruitto the sugar source. In general, treat-ments are not effective if they arenot placed where ants are found.

Sanitation• Eliminate sources of moisture

(such as leaky faucets, plumbing,and free-standing water) and foodbecause these ants are scavengers.

• Clean windows of dead insects.These ants will feed on dead insects.

• Remove the food source if antsare trailing to food. with a mild de-tergent, wipe ant trails after food is re-moved to erase the trail pheromone.The trail pheromone is a specialchemical that foraging ants laydown to guide other foraging antsto food or to a new nesting place.

• Spray the ants with soapywater from a spray bottle. This willoften temporarily halt ant problemsif insecticide use is of concernaround food or other sensitiveareas. Soap breaks the surface ten-sion of the water, causing the antsto drown

• Check potted plants for antsbefore bringing the plants indoorsOne way to check for ants is towater the soil thoroughly to forceants out of the soil.

Physical Exclusion• Caulk cracks and crevices in

the house.• Keep branches from coming in

contact with your house (ants willwalk on them into the house).

Chemical• Apply chemicals judiciously.

Precision spot treatments at pointsof entry into the house such asaround window sills and doorthresholds may be effective.Broadcast spraying for these ants isunwise. A liquid insecticide willmake the area repellent to ants.Ants will not feed on a bait that isplaced in the vicinity of a repellentliquid insecticide.

• Bait stations designed for out-door and indoor use have been re-ported to be effective in killingthese ants. Look for products withdelayed toxicants such as hydram-ethylnon and sulfluramid. The toxi-cant must be slow-acting because ifants die in the immediate area ofthe bait, other ants will avoid thearea and not feed on the bait.

• 1% boric acid in a 10% sugarsolution is a homemade remedy formany sweet-loving ants such as theArgentine ant. There are several dis-advantages to this bait. First, it isvery slow-acting. Second, becausethe colonies are so large, they mustbe given a constant supply, whichmeans the homeowner would haveto repeatedly check on the bait.Even then, control is not guaran-teed. The only advantage is that thisbait is inexpensive.

Characteristics Of The Ideal Ant Bait1. Slow-Acting Toxicant2. Non-Repellent Toxicant3. Preferred Food SourceBaits work because they exploit

the ants’ behavior of sharing foodand nutrients with other ants.Passing nutrients from one ant toanother is called trophallaxis. If food

contains a slow-acting toxicant andthe ant does not detect it, the toxi-cant is passed throughout thecolony by trophallaxis, before killingits members, including the queen.

Ant baits work only if the antseat the bait. Eliminate any alternatefood sources by keeping countersclean and storing food in sealedcontainers.

Professional Pest ControlGood pest control operators have

the training, equipment, and materi-als necessary to perform ant controlsafely and effectively. You may pre-fer to have all of your pest controldone by a professional because ef-fective pest management requiresextensive knowledge of IPM tactics.

If you do contract the services ofa pest control operator, ask ques-tions about the plan to control yourpest problems and get estimatesfrom at least three reputable firmsbefore choosing one.

A L A B A M ACOOPERATIVE

S Y S T E M

This publication was prepared by FaithM Oi, Extension Entomologist, AssistantProfessor, and David H Oi, AffiliateAssistant Professor, both in Entomologyat Auburn University.

Trade names are used only to give spe-cific information. The AlabamaCooperative Extension System does notendorse or guarantee any product anddoes not recommend one product in-stead of another that might be similar.

For more information, call yourcounty Extension office. Look in yourtelephone directory under your county's name to find the number.

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in agriculture and home economics, Acts of May 8

and June 30, 1914, and other related acts, in coop-

eration with the U.S. Department of Agriculture. The

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tus, or disability. UPS, 20M07, New 1 1:97, ANR-999