ANR-1022

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

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IPM Tactics for Subterranean

Termite ControlTermites are among the most economically

important insects in the world. They eat woodand wood-based cellulosic materials. They play animportant role in ecological systems by recyclingback to soil cellulose-containing materials, such asfallen trees. Unfortunately, termites cannot tell thedifference between a pine log in nature and a pineboard that is part of your house. They are bestknown as structural and plant pests that competewith people for shelter and food. Termites causemore destruction to wood and paper products inAlabama than any other insect. They are the mostdifficult and expensive to control. Methods for con-trol of different types of termites differ greatly.Therefore, homeowners must understand termitesand how they can be controlled.

Integrated Pest ManagementUsing an Integrated Pest Management (IPM)

approach is the best way to control termites. IPMcombines the use of multiple available controlmethods into a pest management program. Controlmethods include sanitation, exclusion, structuralmodification, and chemical techniques. IPM focuses on optimization of termite control in an

ecologically and economically sound manner. The integration in pest management practices fortermites usually involves multiple parties and oftenrequires more effort, information, and managementattention than simple application of termiticide.However, once homeowners work through thetransition period, IPM methods are often more cost effective and reliable than chemical-intensivesystems, and they are safer for home residents, pestcontrol personnel, and the surrounding environ-ment. All chemical treatments should only be doneby a professional pest control operator (PCO) whois specially licensed to do termite work. Improperand unauthorized treatments will lead to recurringproblems that will cost more in the long run. If ter-mite treatments cannot be documented as havingbeen done properly, expect difficulties with mort-gage lending companies during sale or resale.

Types of TermitesIn Alabama, there are two types of termites: the

subterranean termite and the drywood or powder-post termite. This publication will concentrate onthe subterranean termites. A summary of their differences is presented in Table 1.

Table 1. Characteristics of Subterranean and Drywood/Powderpost Termite Colonies and Damage

Characteristics Subterranean Drywood or Powderpost

Where found In the wood and in the soil. The wood can be Only within wood members at andboth in the ground and above the ground above ground level; ground

contact not necessary

Distribution All counties More common in south

Moisture requirement High Very low

Colony size Few thousand to millions Few hundred to a few thousand

Area covered Maximum: about 1 acre Confined to wooden member

Evidence of infestation Mud tubes to access Six-sided pellets about the size ofaboveground wood sand kicked out of wood

Infested wood Galleries with soil, usually Galleries without soil, both along the grain across and within the grain

Time to severe damage Weeks to months Months to years

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Figure 1. Typical subterranean termite life cycle

Colony Life Cycle

Worker

Nymph

Soldier

Swarmer orwinged repro-ductive (maleor female)

Reproductiveafter loss ofwings

Supplementaryreproductive(male or female)

Eggs

Immature

King

Queen

Myth #1Subterranean termites require a groundconnection to survive.

In fact, Su & Scheffrahn (1988) estimatedthat 20% of all infestations in South Floridawere aerial infestations, without a groundconnection.

Figure 2. Native subterranean termite swarmers(Courtesy of Demian Knodo)

Figure 3. Formosan subterranean termite swarmers

Figure 4. Formosan subterranean termite primaryreproductives (Courtesy of Weste Osbrink atUSDA/ARS in New Orleans)

The Termite ColonyThe termite life cycle is complicated, including

eggs and immatures that develop into eitherworkers, soldiers, or reproductives (Figure 1).Reproductives (alates) are also known as swarmersbecause they have wings and fly in swarms. Alatesare the primary reproductive form. They willbecome the primary queen and king in a colony ifmating is successful.

Termites are considered “social” insects becausethey live cooperatively in a colony. Other examplesof social insects are ants and honey bees. To livecooperatively, termites have a well-defined castesystem with individuals differing in both form andfunction. In termites, three basic castes occur:reproductives, workers, and soldiers.

Primary ReproductivesPrimary reproductives are the original founders

of the colony. These winged adults are sclerotizedand range in color from honey to black (Figures 2and 3). They are about 1⁄4 to about 1⁄2 inch in length.They themselves neither cause damage to struc-tures nor physical harm to people. After swarming,they land on the ground, shed their wings, and

search for a mate. The successful pair becomes the primary reproductive queen and king (Figure 4).They mate for life and are responsible for producingeggs that become the workers, soldiers, and futurealates of the colony.

Supplementary ReproductivesIf something should happen to the primary

reproductives, supplementary reproductives can beproduced from within the ranks of a mature colonyand take over the reproductive function of the colony(Figure 5). Supplementary reproductives are oftenlighter in color than the primary pair and are com-monly found in clusters of four to six or more. Theability to produce supplementary reproductivesmakes termite control different from ant control.Often, if the queen ant is eliminated, the colony will die. This principle is not true with termites.

IPM Tactics for Subterranean Termite Control 3

Figure 5.Native subter-ranean termitesupplementary

reproductive

Myth #2Subterranean termites “melt” concrete.

In fact, this myth probably arose after a researcher hypothesized in a 1910 publication thatperhaps termites had this ability. We now realize that the soft-bodied termites are simplyadept at squeezing through tiny cracks.

Figure 6. Subterranean termite workers

Figure 7. Nativesubterraneantermite soldier

WorkersWorkers are whitish, soft bodied, and blind

(Figure 6). They are mistakenly called white ants.Workers are the most numerous form in thecolonies and are responsible for performing mostof the labor, such as constructing tunnels andtubes, foraging for food, and tending and feedingthe queen and king, the young, and the soldiers.

SoldiersSoldiers are also soft bodied and whitish but

have large, sclerotized heads with enlarged jawsthat are modified for fighting (Figure 7). They function to defend the colony against intruders.

How to Submit a SampleAlates (swarmers) with wings and/or soldiers

should be preserved in rubbing alcohol when sub-mitted for identification. Submit at least 10 to 15insects. Alates without wings and workers are usually not useful in identification.

Native and Formosan SubterraneanTermites

The most common subterranean termites inAlabama are the native subterranean termites.These termites are a complex of termites belongingto the genus Reticulitermes. The winged reproduc-tives are day swarmers. Swarming begins aroundlate February and continues through May or June.

Most of these termites tend to nest in soil thatprovides a constant source of moisture for thefounding colony. Since moisture is the most impor-tant factor contributing to the survival of subter-ranean termites, these termites can also nest inareas such as leaky roofs. This results in a colony,called an aerial infestation, with no connection tothe ground. Leaky pipes and condensation from airconditioning units also create conditions conduciveto termite survival.

Another termite that is of great concern is the imported Formosan subterranean termite,Coptotermes formosanus Shiraki. The wingedreproductives of this species are night swarmers.This termite is known to occur widely in Mobileand Baldwin Counties, and sporadically in Lee and Calhoun Counties. See Extension publicationANR-1035, “The Formosan Subterranean Termite,”for more information on this species.

Colony Size and TerritoryNative subterranean termite colonies commonly

contain between 10,000 and 250,000 individuals.However, the native subterranean termite is knownto have colonies as large as 5 million individuals,covering more than one-half acre of land. If anative subterranean termite worker weighs 2.5 mg,the total biomass of a colony of 5 million is about16.5 pounds, about the size of a small dog.

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Figure 8. Native (right)versus Formosan (left)subterranean termitesoldier (Courtesy ofGregg Henderson at LSU)

A Formosan subterranean termite colony canrange from fewer than 1 million to more than 10million termites, covering more than 6 acres of land.A colony of about 10 million individuals weighing4.0 mg each would result in a total colony biomassof about 88.1 pounds, about the size of a family ofbeavers (2 adults and 2 juveniles). Ten million indi-viduals is a worst-case scenario.

Identifying the Native Termites andthe Formosan Subterranean Termite

Identification of the two groups of termites issimple. Native subterranean termite soldiers have arectangular head, while the Formosan subterraneantermite has a teardrop-shaped head (Figure 8).Also, when breaking open a piece of infestedwood, if only a few soldiers appear (less than 5percent of termites present), you are probablydealing with the native subterranean termites.Whereas, if many soldiers appear (more than 15percent of termites present), you are probablydealing with the Formosan subterranean termite.

Management of Subterranean Termites

Too many homeowners wait until the damage is obvious before taking necessary actions. If housesare constructed and maintained properly and arepretreated correctly, termite pressure and the risk of termite attack can be reduced or eliminated.

Preventive MeasuresPretreatment

Pretreatment during construction typicallyrequires treatment of soil, under and around thehome, at least two separate applications of regis-tered termiticides (an insecticide for termite con-trol) at the labeled rate by a reputable professionalpest control operator. The purpose of a pretreat-ment is to create a continuous chemical barrieraround the structure that requires protection. Thetermiticides available today do not provide the

same long-term control as did Chlordane, the lasteffective organochlorine used as a termiticide. Itwas banned in 1988. Most currently labeled soil termiticides will protect a structure for approxi-mately 5 years.

Pressure-Treated Construction Timber or Add-OnTreatment

Recently, researchers and PCOs released datashowing that both Borate-treated construction woodand borate application as an add-on treatmentresulted in at least 8 years efficacy against termiteattack. Add-on treatment means to apply a two-foot-wide barrier of Borate to all exposed wood on thelower portions of a structure. Once again, this jobmust be done by certified professional pest controloperators.

Several termiticides are available for pretreatmentpurposes and Borate products for add-on treatments.Consult the current Extension publication ANR-500B,Alabama Pest Management Handbook–Volume 2, forspecific recommendations.

Homeowners must be aware that there is notermite-proof house as long as there are wood,moisture, and wood-soil connection. Keep this inmind during the design and the construction of ahome. Don’t give subterranean termites easy accessto the three things they need to thrive: food, mois-ture, and shelter.

SanitationSanitation is critical to maintaining an environ-

ment inhospitable to termites and, thus, remains ahigh priority. Before and during home construction,remove any wood debris in or near the structure.This includes stumps, roots, or other constructionmaterials such as form boards or grade stakes putin place before concrete is poured. There shouldbe no contact between wood and soil or fill.

Structural Modification• Vapor barriers (vapor retarder) should cover 75

percent of the area under a structure to helpkeep moisture levels down.

• Crawl spaces should be well ventilated to keepthe ground dry.

• Woodwork should be a minimum of 6 inchesabove ground in slab construction and a minimumof 18 inches above ground in crawl-space con-struction (to allow space for future inspections).

• Exterior insulation and finishing systems (EIFS)or synthetic stucco, stucco, or any other sidingmaterial should not run below grade (below thesoil surface). Other common building methods

IPM Tactics for Subterranean Termite Control 5

Myth #3Subterranean termites are attracted to electrical cables.

In fact, they are simply chewing throughthese cables in an attempt to get to a foodsource. Subterranean termites are notattracted to electrical cables nor do theyuse the cables for a food source.

that are a problem when foam is below gradeinclude insulation foam between which founda-tion and wall are poured, rigid board insulation(RBI) that extends below grade, and chambers offoams within concrete blocks. When these mate-rials are installed at or below grade, moisture canwick into the walls of a house creating condi-tions conducive to termite infestation and woodrot. Termites can use foam as a pathway into thestructure by tunneling through the foam. Thesesame conditions make termite inspection, pre-vention, and control extremely difficult if notimpossible. If your house has any of these mate-rials going below grade, get it cut at least 4inches above the soil. Otherwise, do not expecteven a professional pest control operator to takecare of the problem.

House MaintenanceAfter home construction, homeowners can do

many things to enhance termite protection:• Do not disturb the chemical barrier after soil

treatment.• Slope the grade so that the surface water drains

away from the house.• Keep plants, mulch, mulched beds, and gardens

for landscaping at least 12 inches away fromfoundation.

• Keep any wood-based items, such as firewood,scrap lumber, fencing, and planter boxes, fromcoming in contact with exterior siding.

• Divert sprinkler water, air conditioner condensa-tion, and washing machine water away fromexterior walls and foundation.

• Promptly repair any water leaks and moistureproblems in the roof, attic, walls, bathroom, andkitchen.

• Clean gutters and downspouts and keep splashblocks in place.

Inspection and MonitoringHave a thorough inspection done at least annu-

ally to detect possible termite activity, such as mudtubes, swarmers and wings broken off byswarmers, or live termites in an active infestation.Infested wood has a dull, hollow sound whentapped. Monitor stations installed in the ground areanother way of monitoring termite activity aroundyour house.

Methods for Treating Existing Houses

The technique used for treatment depends onwhether your house is on a slab or has a crawlspace. Make sure your house meets the structuralmaintenance requirements above, then ask yourpest control operator for a copy of the label orMSDS of the liquid insecticide or bait with whichthey plan to treat your house. The label will con-tain more detailed information on treatment direc-tions. New nonrepellent liquid termiticides, such asTermidor and Premise, are generating termite con-trol professionals’ interest because of the bold mar-keting programs made by manufacturers promisingcompensation if companies do not achieve at least5 years of effectiveness with their products. Liquidtermiticides provide a quick knockout of termiteactivity. The drawback is that they must be appliedin the way termiticides have been applied fordecades. Often the floors and walls have to bedrilled and a large amount of pesticide applied.Termiticides can kill a broad variety of plant andanimal life if applied incorrectly.

In general, application methods for liquid ter-miticides are as follows:• Trenching and rodding slab construction around

the structure and treating the trench and thebackfill with the amount of termiticide specifiedon the label (Figure 9).

Figure 9. Trenching around a house

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Figure 12. “Long-rodding”

Figure 10.Drilling a slab

Figure 11.“Short-rodding”

• Trenching crawl space construction around theinside and outside of the foundation; treating allsides of the interior supports and plumbing.

• Drilling a series of vertical holes (about 1⁄2 inch indiameter) through the slab at intervals of 6 to 12inches (Figure 10) or in every void of hollowblocks (Figure 11), especially where termites maybe entering. Termiticides may then be “short-rodded” through the drill holes.

Slabs may also be drilled horizontally from theoutside of a structure and “long-rodded” (Figure12). Holes should be drilled between 6 and 12inches apart. Continuous barriers under slabs arealso dependent upon the smoothness of the surfacebeneath the structure (no rocks, tree roots, etc.)because liquids will run the path of least resistance.

Improper construction practices, such as leavingtree stumps under slabs or burying form boards andgrade stakes under the slab, will hamper termitecontrol. There is little that the pest control operatorcan do to rectify a construction error. However, heor she may attempt to use termiticides suspended infoam in an attempt to obtain a better distribution ofthe chemical. Foaming machines are not availableto the general public.

BaitingBaiting systems are a relatively new tool for ter-

mite control. They have been successful in mostcases. Baits are available as in-ground and above-ground products. These systems use wood blocksto monitor for the presence of termites. When ter-mites are found, the wood is switched with toxicbait that the termites eat and take back to sharewith their nestmates, thus killing many termites oreven the entire colony. Successful baiting requirespest control operators to have extensive knowledgeof termite behavior. The toxicants used in baitingsystems are insect growth regulators or slow-acting,nonrepellent toxicants, which are safer than mostof the soil termite killers.

Successful baiting relies heavily on an inten-sive monitoring schedule. In-ground bait stationsare installed around a house at set distances andaround critical areas, according to the bait label.Stations are monitored as often as monthly toquarterly. This rate of monitoring the bait stationsis in contrast to the traditional yearly inspectionof the structure.

Baiting has many advantages. The system isnonintrusive, consumer-friendly, and dramaticallyreduces the amount of chemical needed to protecta structure. With a bait, termites can be controlledwith milligram quantities of active ingredient. Baitsspecifically target termites. The drawback is that itmay take weeks or months to knock out termitepopulations. While baits have been successful ineliminating termites from existing structures, it isstill being researched if termites can be preventedfrom entering a structure that does not have aninfestation. Researchers are also investigating newbaits that will provide rapid colony eliminationover a broad range of termite species, geography,and application timings.

Sentricon, Exterra, and FirstLine are examples oftrade names for bait products. Bait products are alsoon the market for homeowner use. However, seldomis it possible for homeowners to correctly monitorand treat their own houses without the proper equip-ment, training, and knowledge of termite behaviorand habitats as well as effective termiticides.

IPM Tactics for Subterranean Termite Control 7

Other Control MethodsParticle-Sized Barriers

A physical barrier consisting of particle-sizedrocks, such as basaltic rock or granite, can be usedto prevent termite entry. The rocks are ground intoa specific size (16 grit sand) that is large enough sothat termite mandibles cannot grasp it, yet smallenough so that the termite body cannot maneuverbetween the spaces. These particle-sized barriersare used under slabs, around foundations, andaround plumbing to create a physical barrieragainst termites. It is being used in Hawaii duringconstruction. It can be costly, adding several thou-sands of dollars to the cost of a house. The roots of landscape shrubs can compromise the barrier.Particle-sized barriers are not readily available onthe East Coast. Basaltic Termite Barrier andGraniteguard are examples of trade names forthese products.

Stainless Steel MeshTermiMesh is another physical barrier.

TermiMesh is a flexible, corrosion-resistant, high-grade stainless steel mesh that termites do not eatand cannot penetrate or destroy. It is appliedbeneath and around the critical areas, such aspipes, footers, and foundations, to physicallyexclude termites, protecting the structure fromfeeding damage. It is best installed during newconstruction but can be used as post-constructioninstallation by specially trained technicians. It hasbeen successfully used in Hawaii and Australiafor several years. The marketing of this product inthe continental United States is underway. It canbe expensive.

Insecticide-Impregnated Vapor BarriersThis new technology is currently in field tests.

Commercial vapor barriers are impregnated withtermiticide and placed under the concrete slab orwrapped around the bottom half of concrete blocksin the same manner as the stainless steel mesh,thus doubling its function as both an insecticidalbarrier to termites and a vapor barrier.

Borates for Wood TreatmentAt least four products that contain the active

ingredient disodium octaborate tetrahydrate areavailable to pest control operators. Borate productscan be used as a supplemental treatment againsttermites but not as a stand-alone treatment.

Borates can be sprayed, painted, or pressureinjected into indoor wood or wood shielded fromthe elements. The borates diffuse into the woodover a long period of time and provide long-lastingsupplemental protection. Termites die afteringesting borate-treated wood. Borates also protectwood against wood decay fungi and have longbeen used in wood preservation. Borate-treatedwood is also more fire retardant than wood that isnot treated with borates.

The use of borates, however, is limited indoorsbecause of their proleaching properties under wetconditions. Borates are nonselective herbicides, soeven a small amount of borate accidentally sprayedon landscape plantings will kill or damage.

Treatment of Infested TreesOld trees infested by subterranean termites may

be the source of a house infestation. Drill holesinto the tree above the soil line and inject or foamtermiticides into the void created by the termites toeliminate this threat. Once again, this should bedone by a certified pest control professional.

Choosing a Pest Control CompanyCall at least three pest control companies and ask

for price quotes, how the company plans to treatyour house, and what chemical or bait system will be used. Be wary of prices that seem out of line,especially those that are too low. Professional termitecontrol requires specialized equipment and training.A low price may mean low quality. Even whendealing with the Formosan subterranean termite, youcan take 2 weeks to make an educated decision.

Call the Better Business Bureau in your area for any outstanding complaints against a potentialcompany.

A good pest control operator will do aninspection of your property, map areas of termiteinfestation for future reference, and note any areasnot inspected (inaccessible) and structural prob-lems that need repair. Ask for a copy of the reportand map. Keep this information on record.

Be aware that there are many different types of contracts for termite control. Some will offer a“re-treatment only” statement; others may include a “damage replacement” clause. Some will cover allkinds of subterranean termites; others may excludeFormosan subterranean termites. The contracts willvary from company to company and will also varywith the type of construction treated. In all cases,read both sides of the contract and know what you are getting.

Figure 13. Termite damage

For a fee most pest control companies will offeryou an annual renewal service to inspect your housefor future termite attack. Unless you feel you knowall the potential signs and locations common to ter-mite infestations, it is generally a good idea to con-tract for this service. Remember, your home is prob-ably the most expensive purchase you will make inyour lifetime. With a little time and a little knowl-edge, termite damage can be avoided (Figure 13).

ANR-1022

Xing Ping Hu, Extension Entomologist, Assistant Professor, and Arthur G. Appel,Professor, both in Entomology and Plant Pathology, Auburn University; Faith M. Oi,Research Entomologist, with USDA-ARS, CMAVE, Gainesville, Florida, and Thomas G.Shelton, Post Doctoral, Entomology, University of Hawaii

Use pesticides only according to the directions on the label. Follow all directions, precautions, and restrictions that arelisted. Do not use pesticides on plants that are not listed on the label.

The pesticide rates in this publication are recommended only if they are registered with the Environmental ProtectionAgency and the Alabama Department of Agriculture and Industries. If a registration is changed or cancelled, the rate listedhere is no longer recommended. Before you apply any pesticide, check with your county Extension agent for the latestinformation.

Trade names are used only to give specific information. The Alabama Cooperative Extension System does not endorse orguarantee any product and does not recommend one product instead of another that might be similar.

For more information, call your county Extension office. Look in your telephone directory under your county’s name tofind the number.

Issued in furtherance of Cooperative Extension work in agriculture and home economics, Acts of May 8 and June 30, 1914, andother related acts, in cooperation with the U.S. Department of Agriculture. The Alabama Cooperative Extension System(Alabama A&M University and Auburn University) offers educational programs, materials, and equal opportunity employmentto all people without regard to race, color, national origin, religion, sex, age, veteran status, or disability.

UPS, 5M33, Revised July 2001, ANR-1022