RED IMPORTED FIRE ANT BIOLOGY AND CONTROL

James T. (JT) Vogt, Ph.D.

TOPICS OF DISCUSSION

• Brief history of introduction and spread• Basic biology• Dos and Don’ts of control (how biology relates to

control)• Available products, cost considerations• Tailoring control methods to particular situations

FIRE ANT FACTS (introduction and spread)

• Scientific name: Solenopsis invicta Buren• Accidentally introduced into US in 1930s• Stowaway in ship ballast, landed in Port of

Mobile, AL• Currently infests ~250 million acres in US• Is adapting to drier conditions in western areas of

infestation

SPREAD OF S. INVICTA

• Mating flights (wind)• Flooding• Vehicles• Agricultural commodities• Horticultural commodities

CURRENT STATUS OF S. INVICTA (NATIONWIDE)

IDENTIFICATION• Workers are polymorphic, generally reddish-

brown• Mounds (generally) honeycombed inside

Courtesy TAMU

IDENTIFICATION CONT’D• Characteristic stinging behavior

Courtesy Tx. Dept. Agric.

A pictorial key is available from Texas A&M University

BASIC BIOLOGY

• Castes• Reproduction• Nest structure• Foraging and diet

FIRE ANT CASTES• Workers--all female,

young workers tend brood, older workers forage

• Female alates--large winged females

• Male alates--dark in color, small winged males

• Queen(s)--reproductive females

Photo by C. Barr

FIRE ANT ALATES

Photo courtesy of TAMU

FIRE ANT WORKERS

Photo courtesy of S.D. Porter, USDA-ARS

FIRE ANT REPRODUCTION

• MONOGYNE– Single queen colonies– Reproduce via mating

flights

• POLYGYNE– Multiple queen colonies– Reproduce via mating

flights– Reproduce via budding

THE MOUND (GENERAL)• Fire ant colonies do not always build easily-detectable

mounds• Foraging tunnels radiate out from the mound, 2-8 cm below

the soil surface• The soil of the mound warms and dries faster than

surrounding soil• Colonies are located in different parts of the mound during

different times of the day• Mound shape and ease of detection change seasonally

NEST STRUCTURE

Photo courtesy of Texas Ag. Ext. Servc.

FIRE ANT MOUND WITH TYPICAL HONEYCOMBED

INTERIOR

FIRE ANT COLONY HIDDEN IN LEAF LITTER

FIRE ANT COLONY IN SIDEWALK

Photo by B. Drees

FIRE ANT COLONY IN JUNCTION BOX

FORAGING AND DIET (GENERAL)

• Common names for Solenopsis spp.: Lard ants, grease ants (they are attracted to greasy foods)

• Forage year-round, whenever soil temperatures are favorable

• Optimal temp. (2 cm depth) for maximum foraging lies between 70 and 90°F

DIETARY HABITS

• Small arthropods, bits of larger arthropods and dead animals

• A few seeds• Liquid food sources

(nectaries, homopteran honeydew, etc.)

FIRE ANT FORAGERS

THE DOS AND DON’TS OF FIRE ANT CONTROL

(Or, how fire ant biology relates to control methods and decisions)

2 WAYS TO TREAT FIRE ANTS

• INDIVIDUAL MOUND TREATMENTS– Labor intensive– Rapid control if contact

insecticides used– Difficult to find all mounds– Temperature-dependent

• BROADCAST BAITS– Ca. 80-90% effective– Control is slow (2-8 weeks

depending on product)– Controls small, hard to

detect colonies– Can treat large areas– Temperature-dependent

INDIVIDUAL MOUND TREATMENTS

• Dusts, granules, pre-measured drenches, injectible aerosols

• Good if rapid control of a few mounds is required

• Baits can be used on single mounds but control is slower

Courtesy Tex. Ag. Exp. Sta.

BROADCASTING BAITS

• You should use a seed spreader to broadcast baits

• Cannot mix baits with fertilizer or other products

• Best for large areas that don’t require immediate control

DISTURBING THE MOUND

• Don’t disturb mounds prior to any sort of treatment. This will alert the ants to danger, and will decrease the likelihood of hitting the queen and most workers with contact insecticides.

• Do take care to apply dusts, granules, and drenches very gently. This will insure contact with the greatest number of ants--and when baiting, will not distract ants from their foraging activity

READING THE LABEL

• Don’t apply products without carefully reading label instructions. Many products have specialized instructions that should be followed for best results.

• Do consult the label of the product you choose and check for info on timing of application, whether product requires watering in, etc.

BAITING INDIVIDUAL COLONIES

• Don’t apply baits directly to the tops of mounds. This will increase the time it takes for the ants to discover and retrieve the bait and increase the chances of photodegradation.

• Do apply bait products in a circular fashion around individual mounds, approximately 2-3 feet from the mound’s base.

FIRE ANTS IN ELECTRICAL EQUIPMENT

• Don’t treat fire ant colonies in electrical equipment unless you’re a qualified, licensed PCO. Check product label for specific applications!

• Do use materials specifically formulated for fire ants in electrical and utility housings. These include High Tech Insectape ® Insecticidal Strips, JS-685 ®, and Rainbow Fire Ant Killer.

TEMPERATURE AND MOUND TREATMENTS

• Don’t treat individual mounds when it is very hot or very cold outside. The colony will be far underground, lessening the chances of contacting all ants.

• Do treat individual mounds on warm, sunny mornings that follow cool nights. The colony will be located near the top of the mound, where insecticides will have a better chance of contacting ants.

TEMPERATURE AND BAIT BROADCASTING

• Don’t broadcast baits when it is too cold or too hot. Early season applications may not be effective--wait until late May-early June in Oklahoma.

• Do broadcast baits when soil temperature at 2 cm is approximately 80°F (between 70 and 90°F) after monitoring for activity.

RAIN AFFECTS BAITING

• Don’t apply bait products right before or right after a rain. Generally, if rain is expected within 24 h or has occurred in the last 24 h, postpone baiting programs.

• Do apply bait products when the ground is relatively dry. If applying in the morning, be sure that dew is not present on the grass.

GIVE BAITS TIME TO WORK

• Don’t be impatient! Hydramethylnon formulations will take 2 weeks or more to work, and IGRs will take up to 6 or even 8 weeks. Further application within this time interval is wasting $$!

• Do give the foraging ants plenty of time to retrieve and distribute baits. Avoid disturbance of colonies for at least 3 days after baiting, then treat problem mounds individually.

USE FRESH PRODUCTS

• Don’t use bait formulations that were opened more than several months ago, or have been stored in a hot area or left open.

• Do use fresh products whenever possible. Shake bait containers well before opening / using the product. Soybean oil attractants in baits can go rancid and can settle in stored containers.

PRODUCTS AVAILABLE FOR FIRE ANT CONTROL

Mention of any product does not constitute endorsementby Oklahoma State University, Oklahoma Cooperative

Extension Service, or Oklahoma Department of Agriculture.The lists presented here are not inclusive and may change.

Availability and registration of products may change.

BAIT FORMULATIONSCommon insecticides for fire ant control

Trade Name Pesticide ControlAmdro ®, Combat ®,Maxforce®

hydramethylnon moderate-slow

Raid ® , Ascend ® abamectin moderate-slowAward ® , Logic ® fenoxycarb slowDistance ® pyriproxyfen slowExtinguish™ methoprene slow

Restricted use:

SeigePro®, PT® Ascend®, PT® AdvanceTM

INDIVIDUAL MOUND TREATMENTS

Common insecticides for fire ant controlTrade name Pesticide ControlInsecto Formula 7® pine oil suspension slowDiazinon diazinon fastDursban® chlorpyrifos fastOrganics Solutions®,etc.

pyrethrins immediate

Orthene® Fire Ant Killer acephate moderateSpectracide® Bug Stop permethrin fastSevin® carbaryl moderateBionide Rotenone 5 rotenone slow

PCOs have access to many other products labeled for fire ant control

COST CONSIDERATIONS• Cost of product

– Baits: per area basis or per mound basis• $9-15 / acre, $0.50-0.90 / mound

– Drenches, etc.: per mound basis• $0.15-0.25 / mound

• Effort involved in application– generally greater with indiv. mound trt.

• Time involved in application– generally greater with indiv. mound trt.

PLANNING CONTROL EFFORTS TO MEET PARTICULAR NEEDS

• No-tolerance areas– nursing homes, mental health facilities, etc.– Bait 2X / year, inspect monthly and drench any visible

mounds. Encourage client to make improvements in structure, sanitation, etc., as necessary.

• Low-tolerance areas– large green areas assoc. with businesses, etc.– Bait 1 or 2X / year, inspect periodically.

PLANNING CONTROL EFFORTS TO MEET PARTICULAR NEEDS

• Small lawns– Bait 1 or 2X / year, drench problem mounds as they

appear, or combination of both.• Indoor infestations

– Immediately address the threat indoors (treat with a contact insecticide).

– Carefully inspect for mounds outside of structure, in wall voids, etc., and treat.

WHERE TO BAIT?

• Researchers have shown that in order to eliminate fire ant foraging in areas next to polygyne infestations, a 40 m fire ant-free border is recommended!

• In NO TOLERANCE situations, it may be desirable to apply baits in areas bordering the property under contract--also in other situations, to reduce callbacks.

TIPS FOR BAITING NEAR STRUCTURES

• Do not just place bait along exterior walls• Never use outdoor baits inside structures• Be sure to apply at appropriate temperatures!• If necessary, treat border areas to slow re-

infestation.

TIPS FOR INSPECTING• If you can, time inspections for ~2-3 days following a

good rain. New mound construction can be very visible during warm periods following rain.

• Pay particular attention to curbsides, sidewalk edges, and structures, especially where the grounds are frequently mown.

• Placing an attractive substance out and observing the foraging trail can tip you off on mound location.

SUMMARY

• Knowledge of fire ant biology is essential for successful control programs.

• The two primary means of controlling fire ants (baiting and mound treatments) involve different costs and benefits, and can be integrated into a control program

• Tailoring your control program to the specific needs of the client is essential