subterranean termites - a handbook for homeowners

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    Nebraska UniversitySubterranean Termites: Handbook for Home Owners

    Table of Contents

    Preface

    Chapter 1 - Introduction

    Chapter 2 - Termite Identification and Biology

    Chapter 3 - Detecting Termites and Their Damage

    Chapter 4 - Preventing Termite Infestations

    Chapter 5 - Termiticides: Termite Control Chemicals

    Chapter 6 - Conventional Termiticide Treatments

    Chapter 7 - Termite Baiting Technologies

    Chapter 8 - Understanding the Termiticide Label

    Chapter 9 - Are Termiticides Dangerous?

    Chapter 10 - Economics of Termite Control

    Appendix A - Termiticides for Subterranean Termite Control in Nebraska: 20

    Acknolwledgements

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    Preface

    Subterranean Termites - a Handbook for Homeowners is a practical reference for persons who have had little or notraining in insect identification, biology or control methods. In these workshops, we emphasize a common sense approachto dealing with termites and termite control. This handbook has subsequently been revised annually, this being the 2006version.

    The authors are familiar with the scientific literature, and they understand just how easy it would have been tooverwhelm you with technical information. Our goal was to translate scientific jargon into everyday English and to writethis handbook in an interesting style that is easy to read and understand. If you study this handbook from cover to cover,

    you will be better able to understand termite biology and behavior and should be able to successfully select and work witha pest control company to control termites infesting your home.

    Subterranean Termites - a Handbook for Homeowners, can be purchased from University of Nebraska-Lincoln,Extension, in Lancaster County Office, 444 Cherrycreek Road, Lincoln, NE 68528-1507, Phone (402) 441-7180. An orderform can be found at: http://pested.unl.edu/termite/terordfm.htm

    May 2006

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    Introduction

    Chapter 1

    Introduction

    Subterranean termites in the United States causeseveral hundred million dollars worth of damage every year!This includes the cost of controlling them and repairingdamage to structures - including our homes. Based on thecomplexity of todays treatments (both chemical barriersand baits) and the potential consequences of an inadequatetreatment, we believe: 1) a skilled professional is needed toimplement effective termite treatments, 2) homeownersshould work with a reputable pest management professional(PMP) who is experienced with termite treatments, and 3)homeowners should not attempt to treat their homes fortermites themselves.

    A holistic approach to managing termites includes

    building houses resistant to termites, taking measures toprevent termites by eliminating conducive conditions andhaving regular inspections to monitor your home for theirpresence. Understanding termite biology and behaviorand knowing the advantages and disadvantages ofdifferent treatment approaches will help you make betterpest control decisions. Agricultural pest managementspecialists have used this approach for years. This multipletactics approach is called Integrated Pest Management orIPM.The basic components of IPM are:1. Identify and understand the biology and behavior

    of termites - Chapter 2,2. Determine if control is needed - Chapter 3,3. Consider preventative measures - Chapter 4,4. Know the available control measures, evaluate them and

    make decisions about them - Chapters 5-10,5. Implement your chosen control measure - Chapters

    6 and 7; and,6. Evaluate the effectiveness of your control efforts -

    Chapter 3.

    Integrated TermiteManagement

    The barrier method using liquid termiticides wasthe standard termite treatment for much of the 20thcentury. In 1952, chlordane became available and wasthe overwhelming termiticide used for more than 35

    years; its use was discontinued in 1987. It was replacedby chlorpyrifos (Dursban, discontinued in 2005) and anumber of synthetic pyrethroids which are still availablefor use as termiticides. Studies have shown pyrethroidsare very repellent to termites, but are not very toxic. Non-

    repellent products Premise and Termidor came on thescene in the 1990s and are still in use today and comprisethe majority of the liquid termiticides used today.

    The elimination of chlordane lead to increasedresearch and development by chemical manufacturers tofill an empty niche. This effort resulted in the developmenof bait products. The earliest bait was an insect-growthregulator, Sentricon, registered in 1994. The advent ofeffective bait systems has given a new dimension to termitecontrol that was lacking earlier.

    Another type of treatment is to treat structural wooddirectly with borates, which wicks into the wood to protectit from termite tunneling and feeding.

    As time has passed, termite control manufacturershave focused their efforts on finding lower-toxic productsand methods of controlling termites. This search for safeand effective, novel treatments will continue.

    The bottom line: todays termite control professionalsand homeowners have real choices about effectivetreatments they didnt have 20 years ago.

    Concern about IndoorAir Quality

    Todays consumers are concerned about possibledetrimental effects of termiticides on their families andpets. Because of this concern about termiticide, manyconsumers are interested in biological or naturalproducts such as nematodes, pathogenic fungi, insectgrowth regulators (IGRs) and borate products. As a resultless intrusive, natural and other innovative termite controlproducts are becoming more readily accepted by manyconsumers. Unfortunately, science is still scrambling tocatch up with some least-toxic approaches and some triedfor termites, have limited effectiveness.

    ConstructionUnderstanding the myriad of historical and recent

    construction practices is an important componentof termite control. When doing conventional barriertreatments, pest management professionals (PMPs) havehad to contend with rubble or stone foundations, wellsdrain tiles, plenums, wood foundations and common walconstruction. On occasion, construction problems canconfuse even the most experienced PMP.

    The emphasis on energy-efficient structures has

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    resulted in new problems. The use of rigid foam forinsulation around the exterior foundation of homes andother buildings has increased. This rigid foam insulationmakes traditional barrier treatments difficult, if notimpossible.

    Air-tight construction has resulted in increased

    concerns about air quality.Cellulose-based mulch products, such as shredded

    bark placed around the home, can increase termite activityaround the outside of the home.

    The information presented in this handbook isnot intended as an endorsement of any one productover another or the use of one treatment approach. Theuniqueness of each structure may make one treatmentapproach preferable than another, but these are decisionsthat must be left to you.

    Structural anomalies, the location and severity of aninfestation, expedience and cost of control and your ownattitudes about termiticide safety are all factors you willneed to consider.

    As with any major decision affecting your home,we recommend you read and understand as much as

    possible before you make a decision about termite control.Discussions with pest control company personnel maybe helpful, but there is often disagreement about whichtreatment approach should be used. Sometimes companiesare biased toward procedures they are experienced indoing or selling to their clients. You need to sift throughconflicting advice and make your best decision. We havewritten this handbook to help you get started.

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    Figure2-1.

    Thisdiagrams

    howsea

    chnewlyhatchedtermitecandevelopintoanyoneofanumberdifferentcastesdependingonthechangingneedsofthecolony.

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    Chapter 2

    Termite Identification and Biology

    There are over 45 different species of termitesfound in the United States. Only two species, the easternsubterranean termite (Reticulitermes flavipes), and thearid land subterranean termite (R. tibialis), are native toNebraska. This chapter will concentrate on subterraneantermite identification, biology and behavior, factorscritical to making appropriate decisions about termitesand termite control.

    IdentificationTermites are insects. They have three main body parts:

    head, thorax and abdomen. On their head, termites have

    a distinctive pair of straight antennae that look like smallbeads connected together. Since insects dont have a noseto smell their environment, antennae are used as scentorgans, along with other sensory organs on various partsof their body.

    The thorax is subdivided into three segments and isthe part of the body where movement is based. As otherinsects do, termites have three pairs of legsone attachedto each segment on the thorax. The winged reproductives(swarmers) have a pair of nearly identical wings attachedto the last two thoracic segments (see figure 2-1). Thesenearly identical pairs of wings give termites their scientific

    name; the termite order Isoptera, comes from iso meaningequal andptera meaning wings. The termite workers andsoldiers do not have wings.

    The abdomen is where the digestive, respiratory,circulatory and reproductive systems are located. Thetermite digestive system is interesting, because termitesrequire gut symbionts, bacteria and protozoans that havethe ability to break down cellulose into simpler componentsthe termites can digest. Without these microorganisms inthe gut, termites would not be able to feed on wood. Thesemicroorganisms are passed to the larval termites throughthe process of trophallaxis, the exchanging of body fluids.The importance of trophallaxis will be discussed later.

    The reproductive system of the queen is alsoremarkable. After mating, the abdomen of a queenenlarges, and she becomes an egg factory. A mature queenof some species is capable of producing up to 10,000 eggsper week; thats over three million eggs in a year! Since shecan live for a decade or longer, she can produce an amazing3060 million eggs in her lifetime. Neither workers norsoldiers have the capability to lay eggs and are sterile.

    Ants versus Termites. People sometimes confuseants with termites because both live in the soil and theirwinged forms are similar in appearance. Termites and ants

    can also swarm at the same time of year, which adds to

    the confusion. Upon closer examination, there are severakey differences in the appearance of these two distinctlydifferent types of insects.1. Termite workers are white to greyish, whereas ants are

    darker in color. Swarming termites are dark, often blackin color. These are the termites often confused withants.

    2. Termites have straight bead-like antenna; ants haveelbowed antennae.

    3. Ants have a constricted waist where the thorax andthe abdomen are connected; termites have an abdomenthat is broadly joined at the thorax.

    4. Finally, winged ants have forewings (the first pair) larger

    than the hindwings. Winged termites have two pairs owings equal in size and appearance.

    Even though they are similar in appearance and live inthe soil, ants and termites are enemies because many antspecies are predators of termites.

    Social Behavior. Another way termites are similar toants is both are truly social insects. True sociality in insectsis found only in the Hymenoptera (ants, bees, some wasps)and Isoptera (termites). These social insects are amongthe most successful insects in terms of being able to exploittheir environment.

    Termite Identification and Biology

    Figure 2-2. Winged ant and termite swarmer.

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    Grooming Habits. Communication betweentermite colony members is essential for a colony to functionproperly. The queen produces chemical messages that aretransferred to all members of the colony. The spreadingof chemical messages is done through a frequent activitycalled anal trophallaxis, the exchange of fluids from the

    anus to the mouth. Workers lick and groom the queenand then feed and groom other colony members. This is aless than appealing behavior, but it is a very efficient way oftransferring chemical messages throughout the colony.

    Trophallaxis also serves to transfer microorganismsthat live in the gut to all members of the colony. The baitingsystems rely on trophallaxis to distribute bait throughoutthe colony.

    Caste System. A termite colony is highly structuredand has castes that perform distinctly different duties.There are three castes that vary in form and function.Recent studies indicate the caste system in termite coloniesis very dynamic.

    Reproductive Castes. The reproductives produce allother members of the colony and play an important part indispersal and formation of new colonies. There are threetypes of reproductives in a termite colony: the primary,secondary and tertiary reproductives.

    Primary Reproductives. When a colony is verysuccessful, some nymphs (indicated as larvae in figure2-1) will develop wing pads, and at the final molt, turndark and emerge as fully-winged adults the futureswarmers. When environmental conditions are right,often after a period of rainy weather, winged swarmerswill travel through the mud tubes wingless workers have

    built. Instead of shunning the light like worker termitesdo, they break through thetubes, pour out of the soil,and fly off to start a newcolony. In Nebraska, easternsubterranean termites usuallyswarm in April or May, oftenoccurring after a rainy periodwhen the ground is soft.

    After the nuptial flight,the males and females pair onthe ground, and their wingsbreak off at a line of weakness

    near their base. Courtshipinvolves tandem running,where termite pairs run on theground with the male closelyfollowing the female. Whenthe queen finds a suitablenesting location, they stopand excavate a small chamberin the soil and mate.

    During the first few years,a termite colony grows slowly.

    Studies have shown that after two years, there may be onlya few hundred colony members.

    It typically takes four to ten years for a new subterraneantermite colony to produce swarmers, longer if conditionsare unfavorable.

    When termites swarm inside a home, it often means

    the worker termites have found a way inside and there aremud tubes connecting the colony with the structure. It canindicate a serious termite problem.

    Secondary Reproductives. When a colony gets verylarge, the queen cannot lay enough eggs to keep up with thecolonys demand, so sexually competent females and malesare produced called secondary reproductives. The femalesecondary reproductives lay fewer eggs than the queen, butthere can be hundreds of secondary reproductives in anestablished colony. Because of their numbers, they are themost important source of new eggs and allow the termitecolony to increase rapidly in size. They are also importantbecause the reproductive needs of the colony can be

    entirely taken over by these secondary reproductives if thequeen dies.

    The secondary reproductives are smaller than thequeen, but larger than the workers. Both males and femaleslack membranous wings, but some have tiny wing buds.

    The colony consists of a main colony, where theprimary queen lives, and satellite units, where the secondaryreproductives are laying eggs. These are linked togetherby a network of underground tunnels. Over time, theseunits may become isolated from one another to the pointwhere the termites no longer interact. This type of colonyexpansion is called budding, where a number of workers

    or secondary reproductives can be cut-off from the maincolony and form a new, self-sufficient colony.Tertiary Reproductives. When part of the colony is

    cut off from the queen, fully developed workers canbecome reproductives. This process occurs on-the-spotrequiring no interaction with the queen or the originalcolony. The resulting ergatoid (tertiary) reproductives arewingless and look like big workers. They can produce twoto three times more eggs than primary queens, however,this accelerated reproductive rate may be short-lived.Research is on-going to learn more about this process.

    Worker Caste. Workers are the most numerous castein a termite colony and are white or cream-colored, soft-

    bodied and prone to desiccation (dehydration). They arealso blind and wingless. To prevent desiccation, they liveunderground, inside wood or inside the mud tubes thatthey construct. They are rarely seen unless infested woodis examined or mud tubes are broken open.

    Most termite workers spend their entire lives feedingand maintaining the colony. Workers forage for all thefood that feeds the entire colony. They also constructmud tubes, excavate chambers and repair the nest whendamaged. They feed all the colony members and groomand take care of the young nestmates. The young workers

    Figure 2-3. Termiteswarmer reproductive.

    Figure 2-4. Queen termite(left) and king termite.

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    stay in the colony, caring forthe eggs and nymphs whilegrooming and feeding others.The older, stronger and largerworkers construct the nest andforage for food. Termite workers

    reach maturity within a year andcan live about two years.

    Soldier Caste. In strongcolonies, some nymphs willdevelop into wingless, light-colored termites with large headsand brown, well-developed jaws.They are larger than workers.These soldier termites defendthe colony from attack by ants orother termites. The soldiers are

    much less numerous than the workers. They hide withinthe mud tubes and in the nest and will not be seen unless

    the wood or mud tubes are disturbed.

    BiologyTemperature. Like other insects, termites are

    cold-blooded, meaning termites live and forage in thesoil at a temperature comfortable for them and will notbe found where the temperatures are too cold or too hot.During the winter, in northern areas of the U.S., termitescannot cross a frost barrier to forage at the soil surface butmay be active deeper in the soil. When temperatures warmin the spring and summer, termites will be found near the

    soil surface.This temperature effect means firewood stackedoutdoors cannot have active termites in it in the middleof the winter when temperatures are below freezing. Italso means many termite infestations in Nebraska areseasonal and are active only between March/April throughOctober/November. Another fact is termites are not likelyto find bait stations placed at the soil surface during coldermonths of the year, although the termites may be active atdeeper soil levels.

    Heated basements can create an environment wheretermites, having entered the basement through cracks inthe foundation below the frost line, can feed year round

    undetected and uninterrupted by cold winter conditions.This, coupled with our inclination to finish our basementsby covering walls and ceilings, creates optimal conditionsfor termites to do serious damage and remain activethroughout the year.

    Moisture. To maintain a moist environment abovethe ground, workers continually carry moist soil aboveground for use in constructing mud tubes. This termitemud is tiny particles of soil, wood or debris cementedtogether with saliva and fecal matter. In addition to buildingtubes, termites leave mud in wood they have excavated.

    This mud is so characteristic that termite-damaged woodcan be readily identified even if no termites are found withit. Active termite tubes are kept moist to maintain a highhumidity in the gallery system.

    If the wood above the ground is moist enoughsubterranean termites can survive and multiply indefinitely

    with no direct-ground contact. These above-groundcolonies are called satellite colonies. Since they require aregular moisture source, these above-ground colonies arequite uncommon. The presence of secondary queens otertiary reproductives can be a sign of a satellite colonyTreating an above-ground satellite colony is difficultbecause barrier treatments nor baits placed in the soilwill eliminate their feeding. To eliminate a satellite colonyrequires you first solve the water problem allowing thecolony to live above the ground.

    Because of moisture needed by termites, houseswith water problems near the foundation and overgrownvegetation too close to the house, may be more at risk

    More information can be found in Chapter 4, PreventingTermite Damage.

    Searching for Food. Researchers have traditionallythought termites move randomly in the soil. This wasbecause it is virtually impossible to see how these soil-dwelling insects actually travel in the soil. But recentlystudies have shown termites actually move in verypredictable ways. Scientists have discovered their movementis much more efficient than if it was merely random. As theytravel away from the colony, termites construct branchingtunnels in a radial pattern similar to the spokes in a wheelThis pattern evenly divides and sub-divides the search area

    so the termites cover it as completely as possible.Termites probably dont detect wood from appreciabledistances because the soil environment doesnt allowchemical cues to travel very far. They certainly cant tellwhere your house is. We think termites find food by almostbumping into it during their foraging activities. Termitesalso tend to travel along below-ground objects, like rootsstones, basement foundations, pipes and other objectsbecause it is easier to follow these objects than to tunnelthrough soil. They may avoid areas that are extremelycompacted.

    Termites respond to environmental cues, liketemperature and moisture gradients. During Nebraskas

    winters, they move down into the soil because they cannotcross the frost barrier. During dry periods, termites movedeeper into the soil or seek artificially moist areasforexample, in well-watered gardens. During the summer inNebraska, termites will be found in the upper soil levelswhere most roots are found.

    Once termites find food, they will stop and feed. Moretermites will be sent to the food-rich area. Marginal foodresources may be abandoned, although, once they have aconnection with a food source, they will be able to findthe food again if needed. During the winter, some food

    Figure 2-5. Workertermite (left) andimmature termite.

    Figure 2-6. Soldiertermite.

    Termite Identification and Biology

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    resources will be abandoned because of cold conditions,but feeding may resume the following spring or summer.Seasonal feeding is why inspections during the winter arenot as likely to find live termites as in the late spring orsummer.

    If termites come across a physical barrier in the soil, like

    a basement foundation, they may either move horizontallyalong it, or they may move vertically up the foundation. Ifthey find a crack in the foundation greater than 1/64-inch,they may explore it. If their mud tube becomes exposedto dry air, they may stop and change direction to avoiddesiccation.

    Food Preferences. The main nutritional ingredientin the food termites eat is cellulose, the hard structuralcomponent of wood and other plant tissues. Termites willfeed on nearly any source of cellulose, including wood,roots, twigs, mulch, paper, cardboard and fabrics madeof cotton and other plant-based materials. Subterraneantermites have been found infesting living trees, but it is

    unclear whether they destroy living tissues or are feedingonly on dead areas.

    Subterranean termites tend to prefer softer woods overhard wood, but no untreated wood is completely resistantto termite attack. They typically eat the softer springwood and leave the harder summer wood which results inthe wood being hollowed out between the growth rings.Termites are most attracted to wood partially decomposedand attacked by fungi; studies have shown they thrive ondecaying wood. Wood that is on or in the soil or has beensaturated with water is much more suitable for termitesthan dry, structural wood. Some types of wood (redwood,

    cypress, junipers) are more resistant to termites because ofnaturally occurring substances in them. However, duringthe weathering process, the repellent substances (oils andresins) leach, and the wood loses its resistant quality.

    Even though termites feed on cellulose, they canpenetrate and damage non-cellulose materials, includingplaster and drywall, stucco, plastics, neoprene and rubber.Termites will damage vinyl swimming pool liners, poolfilters and heater lines. Softer metals, such as lead, copperand aluminum, have been damaged as well as linoleum,

    asphalt, PVC pipes and rigid board insulation constructedof polystyrene (Styrofoam).

    Damage. The amount of damage termites can do to astructure depends on a number of factors.

    1. Colony size. It should be obvious the more termitesthat feed on the structure, the more damage that is done.Within a colony, it is not likely all the termites are feedingon only one source of wood. Alternative food sources in thearea, like dead tree stumps and roots, mulch and woodpiles,increases the number of food sources for termites.

    What is the size of a termite colony? A lot of researchershave attempted to calculate how large termite colonies are.This is no small task, because of the underground nature

    of termites. One expertMichael Potter, University ofKentuckyhas concluded the sizes and foraging ranges oftermite colonies are highly variable. Some colonies havebeen estimated to have hundreds of thousands to millionsof individuals with a foraging range of up to half an acrein size. Other termite colonies are smaller and may haveonly 10,000 individuals that may travel less than 20 feet.Because they are highly variable, it is difficult to generalizeabout the size of an average termite colony.

    2. Duration of feeding. In northern climates, likeNebraska, many termite infestations may be seasonal,unless of course, termites have entered the structure below

    the frost line.3. Type of termite. Some termites have greater appetitesthan others. For example, the Formosan termite found inthe southern U.S. is much more aggressive and eats morethan the subterranean termites found in Nebraska.

    There are few studies that have documented thedamage from subterranean termites in the Midwest. Mostof this kind of research comes from southern states. A 1996research study in Georgia monitored wood consumptionby subterranean termite colonies by putting pieces ofwood below the ground. This study examined 60 termitecolonies over a three-year period. The researchers foundthe average amount consumed per colony was equivalent

    to one five-inch section of pine 2x4 each year. If this studywere done in Nebraska, we would expect this amount to beless, because of the climate differences already discussed.In addition, subterranean colonies in Nebraska may belarger or smaller than the ones (average less than 100,000termites) that were looked at in Georgia.

    Figure 2-7. Termites feeding on wood.

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    Chapter 3

    Detecting Termites and

    Their Damage

    Detecting Termites and Their Damage

    It has been estimated 1720 percent of Nebraskahomes have either had a termite infestation sometime inthe past, or will have a termite infestation sometime in thefuture. Because of this, it is extremely important to carefullyexamine every home for termites or termite damage. This isthe only way to detect the presence of termites and preventfuture structural damage. The authors suggest every homebe inspected annually by a qualified termite inspector.However, we also believe homeowners should be foreverdiligent and always be on the lookout for termite activity.

    The homeowners, after all, live in the house 24 hours-a-day. They are the ideal inspectors because they are themost familiar with all parts of the house.

    This chapter provides the necessary information so theaverage homeowner can successfully inspect their homesfor termites and/or termite damage.

    What is Needed for theInspection?

    Whether done by you, the homeowner or a professional

    inspector, the number one thing required for a successfultermite inspection is careful thought (use your head!).Termites try to stay hidden. Everything they do hides theirexistence. You must use everything learned in this chapterto help detect their presence.

    Essential items needed to do an inspection are a brightflashlight; a flat-bladed screwdriver; a pencil, clipboard,graph paper and a tape measure. The flashlight allows theinspector to examine all the nooks and crannies wheretermites hide. The screwdriver is used for probing (morelater on this). The other items are for constructing anaccurate scale drawing of the house.

    Some other useful items are a hard hat to protect your

    head in low clearance areas, a pair of gloves and coverallsto protect your hands and clothing, a trim prybar andhammer for removing trim boards, baseboard or otherwood coverings, and a ladder or step ladder for easieraccess of some areas within the house.

    Additional high end items sometimes used byprofessional inspectors include a moisture meter, a fiberoptic viewing device, microwave pestfinder and termite-sniffing dogs. The moisture meter can detect high moistureinside walls without opening the wall. High moisture isa good indication of termite activity. The operator must

    receive special training before the meter can be usedproperly. A BoreScope (fiber optic device) allows theinspector to visually look into void areas for evidence otermites. The pestfinder allows the inspector to beammicrowave signals through walls to see termites andother wood destroying insects. The termite-sniffing dogsare used to literally sniff out the termites.

    Inspection TargetsThe inspector is primarily looking for two things: live

    termites and signs of termites. If any of these are spottedwe suggest hiring a professional inspector to assurenothing is overlooked. Live termites are sometimes spottedoutdoors when soil is disturbed around wood that touchesor penetrates into the soil. Live termites are also sometimesseen during remodeling activities or if a termite mud tubeis disturbed. The other time you may see live termites isduring swarming (see Chapter 2).

    There are three main signs of termites that can beseen during an inspection: shed termite wings and/or deadswarmer termites, termite mud tubes and termite damage

    During the swarming season, termites shed their wingsThese wings become very important as an indicator otermites. The wings can be anywhere (inside or outside)but a good place to start looking is in window sills. Thewings/dead swarmer termites will also sometimes fall intospider webs.

    Figure 3-1. Swarmers in a window sill.

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    Termite Mud TubesMud tubes (also called shelter tubes) are constructed

    by worker termites (see Chapter 2). These tubes are anobvious indication there is termite activity in the area.These tubes will be evident anywhere there is a connectionbetween the termite colony in the ground and any woodenfood source. The tubes can be constructed on the surfaceof concrete, metal, wood, plaster, brick or almost any othermaterial. They can be inside cracks (termites can fit throughany opening 1/64th of an inch wide or wider) in concreteor wood, inside building materials such as insulatingmaterials and wooden supports or between walls or floors

    in void areas.There are several types of shelter tubes: utility/workingtubes, exploratory/migratory tubes, suspended/drop tubesand swarming tubes.

    Utility tubes are often very wide. They carry hundredsto thousands of termites daily. Typically, the utility tubehas lanes inside, withsome lanes handlingtermite traffic going upand some lanes handlingtermite traffic going down.These lanes are not aswell organized as our

    highway system, but thetermites do tend to stayin well organized caravansas they move up anddown the tube. Termitesmoving up are carryingmud and water from thesoil for use in further tubeconstruction, whereastermites moving down

    are carrying food (wood andcellulose material).

    Exploratory tubes areusually only about twotermite-widths across. Thesetubes are constructed to

    facilitate finding foodsources. These tubes havebeen seen traveling 15 feet ormore above ground (tubingover metal or concrete) toreach a desirable food source.Freestanding exploratorytubes can be 35 feet up fromthe soil surface. Exploratorytubes can be built from thefood source down to the soil.Suspended/drop tubes are aspecial type of exploratory

    tube that are constructed to add more access tubes to andfrom an existing food source.

    Swarming tubes are side branches constructed offexisting tubes. The end of the swarming tube is opened tothe atmosphere at the time of swarming.

    Termite DamageTermite damage can be either inactive or active. It

    often takes an experienced inspector to tell the difference.Termites can damage softwood and hardwood lumberproducts, masonite paneling, composition siding and

    other construction materials within a house. They can alsodamage such cellulose materials as books, paper, cardboard,wallpaper and the paper covering on drywall.

    The wood or cellulose that has been infested withtermites is usually damp and invaded by fungi. Termitesfeed in the larger, softer areas of the wood first (between

    the tree growth rings of the wood). The resultingdamage appears lattice-like. As the wood is eaten,the empty spaces are replaced with soil. Wood israrely completely eaten and the size and shape ofthe wood is maintained. Usually they only eat about1020 percent of the total wood volume. Termite

    Figure 3-4. Termite-damaged wood. Figure 3-4. Carpenter ant-damaged wood.

    Figure 3-2. Termite mud tubes. Figure 3-3. Termite mud tubes above adoor frame.

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    damage is easily distinguished from otherinsect or rot damage.

    Carpenter ant damage is distinctlydifferent from termite-damaged wood.Occupied galleries are kept very clean,resulting in the surface having a polishedlook (see Figure 3-4). These ants prefer to infest wood thatis moist and rotting and will sometimes use wood that hasbeen hollowed out by termites. They push sawdust andother debris out of their galleries, often resulting in a cone-shaped pile accumulating just below the nest entrance.

    Probing and Sounding

    Tapping exposed wood by firmly hitting parallel tothe grain with a screwdriver (probing) is an importanttechnique used during termite inspections. If the woodhas been damaged, the blade of the screwdriver will

    penetrate into the wood. Tapping wood byhitting with the blunt end of the screwdriver(sounding) is another technique usedSounding will tell you where the wood may

    have been damaged. The inspector will heara hollow or dull sound indicating possiblehidden termite damage. If either probing orsounding indicates possible hidden damage

    probe further for tunnels, galleries or termite mud termitesleave behind as they feed.

    Where Should You Look forDamage?

    Termites usually do more damage to areas closer to the

    soil. Therefore, the most commonly infested areas in homesare exterior walls, areas near cracked foundations/slabssill plates and joists, walls common with garages/additionsand areas near porches. However, if there is a problem thatcreates a buildup of moisture, like a plumbing leak or leakyroof, the termites may gravitate toward these areas (moreabout moisture problem areas in Chapter 4).

    Quick Inspection GuideWhat do I need?

    Flashlight Flat bladed screwdriver

    What are the signs of termites? Shed termite wings and dead swarmer termites Termite mud tubes Termite damage

    Where do I look for damage? Window sills are a good place to look for termite wings. Wings and dead swarmers often fall into spider webs. Mud tubes are evidence of an active termite infestation. Termites can damage softwood and hardwood lumber

    products, paneling, siding, books, cardboard, wallpaperand paper covering on drywall.

    Detecting Termites and Their Damage

    Figure 3-5. A screwdriver is a useful tool forinspections.

    Figure 3-5. Termite-damaged wood showingtermites preference for the soft wood parts.

    Figure 3-7. Termite-damaged paneling.

    Figure 3-6. Termite-damaged paper.

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    The most commonly infested areas are exterior walls,near cracked foundations, sill plates and joists, walls nextto garages and areas near porches. Also places wheremoisture builds up such as plumbing leaks and leakyroofs.

    How do I find the termites?

    Tap exposed wood by firmly hitting parallel to the grainwith a screwdriver.

    If the wood has been damaged, the blade of thescrewdriver will penetrate into the wood.

    Tapping the wood by hitting with the blunt end of thescrewdriver will help you hear hollow or dull soundsindicating possible hidden termite damage.

    What do I do if I find live termites? Use a tweezers to carefully pick up several of the insects. Place them in a small container and close the cover

    tightly. Bring the sample to the Termite Workshop or your local

    county extension office for identification.

    The Inspection Look for wood-soil contact areas. Be especially wary of foundation walls that are of

    hollow-block construction. Termites frequently enterwood through the voids in the blocks and are very hardto detect.

    Check each room inside for damage, decay and excessivemoisture.

    Look at baseboards and around door/window frames. Look for termite-damaged wood and/or water stains.

    Check all walls, ceilings and floors. Look for cracks in the baseboard (could indicate excessivemoisture and/or feeding damage).

    Look for raised paint or wallpaper (termites can eatpaper and leave paint behind).

    Look for ripples in paneling and wallboard (caused bymoisture/termites).

    Look for drywall ripples or tiny holes in surface ofdrywall or wall paper (termites seal holes with mud afteremerging through the paper).

    Probe wall plates (board at bottom of walls) with ascrewdriver.

    Pry back the baseboards and window/door trim boards

    if possible, especially if you suspect termites and/ormoisture problems.

    Probe sill plates and joists with the grain of the woodusing a screwdriver every foot or so.

    Check for structural sagging, buckling, or settling. Check for improper ventilation in crawlspaces and

    correct if necessary. Note plumbing and utility fixture entrances and passages

    through the basement floor and the foundation. Look around showers and tubs. Be sure to check closets as well.

    Walls constructed of stone, concrete, cinder blocks,hollow tile, or brick may develop cracks through whichtermites can pass to sills and other wood members;carefully inspect such walls.

    Check plumbing for leaks/condensation. Spend extra time inspecting areas around porches.

    Earth-filled porches and steps account for more cases oftermite attack than any other building feature.

    Check all perimeter walls carefully. Check wood panelingand other wall finishings on basement walls, wood parti-tion walls and other wood construction in the basementthat extends from masonry to the sills or joists.

    Look for moisture problemsproper grading, downspouts, poor drainage.

    Check sheathing of eaves, chimneys, and vents. Record the outside dimensions of the house. Compare

    outside dimension of house with inside measurements todetermine if there are any hidden areas that may provideaccess to your home for termites.

    Remember Termites are constantly foraging, just because you didnt

    find termites last year doesnt mean that you wont findthem this year.

    Lots of things can help to make it easier to inspect fortermites or provide a sign they are present: use of termiteshields, establishing 6-8-inch gaps between soil and woodparts of the house, and eliminating vegetation near theexterior foundation (more on this in Chapter 4).

    The average home takes two hours to completely

    inspect. Inspect your home at least once a year. Even if an infestation is found, the inspection should be

    complete and thorough to ensure all points of entry anddamage have been found.

    A light infestation may escape detection even with carefulinspection.

    Termite workers attempt to remain concealed.

    Figure 3-8. Termite-damaged wood. A mud tube hasbeen opened, exposing a worker termite.

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    Preventing Termite Infestations

    Chapter 4

    Preventing Termite Infestations

    Since termites are most active in the soil, the basementis often the place termites infest. When we build homeswith basements, we keep them warm in the wintertime.This means termites entering a basement below the frost-line can remain active and continue feeding even whenthe weather is very cold outside. The only basementimpervious to termites is one completely sealed and thathas no cracks in it; a rarity, because there is nearly alwaysa crack somewhere in the foundation or basement slab.Foundations help prevent termite infestations, but mostfoundation types have special problems associated withthem.

    Basement FoundationsPoured Concrete Foundation. This is the most

    difficult foundation for termites to find a way through,but only if walls have no cracks in them. Remember thattermites can enter through very small cracks. To makeconcrete more termite proof, builders should reinforcethe poured concrete with steel rods to prevent opening of

    joints or cracks due to shrinkage.Block and Brick Foundations.These basement

    foundations are at risk because cracks often develop as the

    foundation ages. With hollow blocks, termites can enterthrough a crack and follow the hollow spaces vertically andenter a house virtually undetected. Where hollow blockmasonry is used on new construction, it should have asolid capping of four inches of reinforced concrete.

    Crawl Space. Crawl spaces are often insufficientlyventilated, which makes them ideal environments fortermites to tube vertically. In many crawl spaces, the spacebetween the soil level and horizontal timbers is inadequateto prevent termite tubing. Experts recommend an 18-inchvertical distance between the soil and structural wood.

    Slab. Slab construction results in structural woodtimbers fairly close to the soil level and makes this type of

    construction at high risk of termite infestations. Commonconstruction techniques serve to create termite entry intothe structural part of the home. When framing walls, buildersoften nail lumber to the slab with a nail gun. Nailing intothe slab may weaken the slab and create cracks that allowstermites to have easy access to construction lumber.

    Finished Basements. Finished basements area problem because inspection is so difficult. Termiteinspectors will not give complete assurance a structure isfree from termites because termites might be active behindfinished walls and impossible to see. To make a finished

    basement more termite proof, consider the following: Finished basement walls should be supported on a

    concrete base rather than nailing lumber into thebasement slab, which often results in cracking. Nailinglumber into foundation walls may also cause cracks.

    Repair cracks in basement walls, floors before covering. Use pressure-treated lumber in all below-ground

    construction (see the Termite Resistant Materials sectionlater in this chapter).

    Eliminate Conducive

    ConditionsLike other animals, termites need food and water to

    survive and thrive. Subterranean termites are most plentifuin natural woodlands where there is an abundant supply ofboth. They rarely need to feed on wood above the groundbecause so much wood on or in the ground is readilyavailable. In northern climates, cold winter temperatureslimit termite activity because, like other cold-bloodedorganisms, termites arent active when the temperature isbelow 50 degrees F or so. They cannot cross a frost barrierduring the wintertime, so much of the termite activity in

    Nebraska occurs between April and October.When we build houses, we clean up most of termitesnatural sources of food so the wood that we leave forthem is the wood in our homes. Unlike the abundanceof wood lying on the ground in woodland settings, thewood in structures is usually not that easy for termites tofind. Termites must find cracks in basement foundationsor concrete slabs to allow them access to constructiontimbers. When traveling in dry air, termites construct andtravel in mud tubes and avoid desiccation by keeping thetubes moist. Understanding the importance of food andmoisture in termite survival will help you understandconditions conducive to termite infestations and take

    actions which may prevent infestations.Eliminate Wood to Ground ContactStudies have shown about 90 percent of structural termiteinfestations can be traced to wood that is in contact withthe soil. Wood-soil contact provides termites easy accesto food and water from the soil, and frequently, a hiddenway into the structure. Wood siding, latticework, door andwindow frames and other wood should be at least six inchesabove the grade level. Eliminating wood-soil contact canrequire regrading or pulling soil or mulch away from thefoundation.

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    When inspecting your property, look for areasthat wood and soil are in direct contact. Consider thefollowing: Wood posts and other structural elements should

    never penetrate concrete floors (basements and slabconstruction homes, garages). Replace with metalposts but be sure to remove all wood imbedded in theconcrete.

    Be sure to check basement windows and frames. Theyshould be made of metal or pressure-treated wood.

    Outdoor wood porches and steps should be supportedby a concrete base, at least six inches above grade.

    Where wood-to-soil contact cannot be eliminated, treatedwood should be used. For more information, see thePressure-Treated Lumber section, later in this chapter.

    Remove Wood Debris. All wood or cellulose

    material left on or below the soil surface provides aconvenient source of food for termites. Constructiondebris in the form of wood scraps as well as stumps, roots,cardboard boxes and newspapers should be removed fromunder and around the building. Be sure to check undercrawl spaces and porches. In new construction, woodscraps should never be buried in the fill (Figure 4-2). Stackfirewood above the ground on a cement slab and store thefirewood away from the house.

    Remove Vegetation and Mulch. Shrubs,vines, trellises and other dense vegetation should beremoved from the side and foundation of the house.Vegetation traps moisture, which is attractive for termites.

    Dense vegetation makes it more difficult to inspect thehouse and detect their presence. Plants near the house alsomay need watering, which brings moisture close to thefoundation and may increase termite activity.

    What About Mulch? Mulching with shredded wood orbark chips around bedding plants, trees and shrubs is usedbecause mulch is attractive, holds moisture, insulates soilfrom extreme temperatures, and prevents weed growth.However, mulch also serves as a food source for termites.In addition, the moisture-holding properties of wood/barkchips and insulation may increase the attractiveness to

    termites in mulched areas. How should you manage

    mulch next to your home to prevent a potential termiteproblem?

    Studies at the University of Maryland compareddifferent types of mulch, including pea gravel. Researchersfound termite activity was greater under all types ofmulch compared with bare soil, because soil moisture wasgreater in the mulched areas. Based on these studies, theyconcluded it is best to have bare soil next to foundations.This reinforces the need to slope soil away from the houseand use gutters and downspouts to move rainwater awayfrom the house and keep the foundation area dry.

    Termite prefer solid pieces of wood over mulch. Many

    experts suggest using no more than three to four inches.The type of wood mulch may also influence termitefeeding. Cedar, cypress and redwood mulches may besomewhat resistant to termites initially because these woodshave resins that may make them less palatable. However,over time, these resins leach into the soil. According toMichael Potter, termite researcher at the University ofKentucky, no wood or plant-based material is immune totermite attack.

    Because insecticides quickly break down underultraviolet light, spraying insecticides on mulch to preventtermite activity is of little value and not recommended.

    Eliminate Moisture Problems. Termites are

    more likely to infest a structure if the soil around it isconstantly moist. Make sure water drains away from thebuilding. Check to make sure gutters and down spouts arein good repair and divert water away from the building.

    Roof or plumbing leaks can enable termites to surviveand colonize structures above the ground without soilcontact. A termite inspector may be able to detect suchmoisture problems in the wall with a moisture meter.

    Humid conditions in a crawlspace can promotetermite problems because termites are able to constructlonger mud tubes. Humidity in crawlspaces can be reduced

    Figure 4-1. Avoid direct wood to soil contact.

    Figure 4-2. Termite colonies can develop in wood debris.

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    by providing adequate ventilation and creating a vaporbarrier. Most building codes call for one square foot ofvent opening per 150 square feet of crawlspace area. Vaporbarriers can be created by covering the soil with 4-6 milpolyethylene sheets.

    Remedy Difficult or Unusual Construction

    Problems. Termite infestations can get started becauseof the way a building is constructed. Sometimes unusualconstruction will make it difficult or impossible to treatwith a chemical barrier. Remodeling portions of an existinghome may prevent future termite problems.

    Increase Crawlspace Clearance. A condition thatpromotes termite infestations is inadequate clearancebetween the soil surface and the structural wood above acrawlspace. Too little clearance makes it difficult to inspectproperly. In addition, it is easier for termites to tube overthe foundation to get to the wood. A minimum of 18 inchesshould exist between horizontal timbers and the soil. Youmay need to excavate soil to achieve this distance.

    Replace Dirt-filled Porches and Steps. A significantpercentage of failed chemical barrier treatments are relatedto dirt-filled concrete porches or steps. This constructionproblem brings the soil in the porch or steps above theexterior wall of the building and near the structural woodof the house. When termites have entered the home fromthis construction problem, it can be particularly difficultto treat it properly. One possible solution is to remove andreplace the porch or steps.

    Eliminate Stucco or Brick Below Grade Level. Stuccoor brick veneer that extends below the soil level is anotherway termites can get into a structure because a crack may

    form between the brick veneer or stucco and the structure.It may be necessary to excavate soil away from thefoundations or remove lower rows of brick.

    Remove or Replace Rigid Board Foam Insulation.Since the early 1980s, the use of rigid foam insulation hasincreased in new home construction to increase energyefficiency. By 1992, 50 percent of all new construction

    contained some type of foam insulation. Panels of thistype of insulation are typically installed on interior orexterior foundation walls, but all construction types (slabscrawlspaces and basements) are likely to contain rigidboard insulation. Termite problems arise when exteriorinsulation panels extend below the soil line because

    termites may tunnel undetected through or behind it intothe structure. Termites living behind these foam panelscan avoid the chemical barrier, and chemical treatmentscannot penetrate the foam because it resists wettingMethods of controlling termites behind below groundinsulation are difficult at best, and some companies mayrefuse to use a barrier treatment on structures with foaminsulation or provide no guarantee of treatment. Oneremedy is to excavate and remove the insulation panels.Another option might be to use or replace insulationpanels with panels impregnated with boric acid.

    Termite Resistant MaterialsPressure-Treated Lumber. One way to prevent

    termite damage is to use pressure-treated wood wheneverwood comes within six to twelve inches of the soil. It isa good idea to use pressure-treated wood when finishingbasements. There are excellent reasons for using pressure-treated lumber. Pressure-treated wood is resistant to termitesand decay so its use extends the life of our forests.

    There are several types of treated wood the homeowneris likely to encounter.

    Creosote. Creosote-treated wood was the firstdeveloped and is still used for railroad ties, highway bridges

    and marine structures like docks and sea walls. Usedrailroad ties are often sold to homeowners who use themas inexpensive landscape timbers. Creosote-treated woodshould be resistant to insect feeding and decay althoughrailroad ties may house carpenter ant colonies becausecarpenter ants do not feed on the wood, but tunnel into itto build a colony.

    Chromated Copper Arsenate (CCA). CCApressure-treated wood has a greenish cast and is highlyresistant to termite infestation and decay. Invented in1933, CCA-treated wood has been widely available sincethe 1970s; literally millions of decks have been built ofCCA-treated wood. The copper acts as the main fungicide

    and also provides some protection against termitesArsenic provides protection against termites and copper-tolerant decay fungi. Chromium helps to bond and fixthe chemical components to the wood. The problem isarsenic is a known carcinogen.

    The Environmental Protection Agency and the leadingcompanies in the wood-preservative industry came to anagreement to remove all residential use and sales of woodproducts treated with CCA (Chromated Copper Arsenate)ended as of January of 2004. However, CCA-treated woodproducts will be still available for use in some industrial,

    Figure 4-3. Provide adequate clearance betweenwood and soil.

    Preventing Termite Infestations

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    highway, and agricultural applications. These uses willinclude wood used as poles, piles, guardrail posts, andwood used in saltwater marine exposures.

    This decision by manufactures to phase out the useof CCA-treated wood for residential structures has peopleasking what to do with existing structures made from

    pressure-treated wood. The EPA does not suggest tearingdown structures made of CCA-treated wood. Many feelthat applying coatings and sealants to the wood mightminimize any chance of exposure to arsenic, although thisis a topic of some debate. According to the EPA, peopleshould take common sense precautions, especially whenit comes to children. Kids should wash hands after playingon structures and keeping food from direct contact withCCA-treated wood.

    Alkaline Copper Quaternary (ACQ). Thistreated wood has been used successfully for more than10 years. Although it looks like ordinary pressure treatedlumber, ACQ does not contain chromium or arsenic

    which is used in CCA-treated lumber as a preservative.Instead, it is a mix of copper and a quaternary ammoniumcompound, nicknamed quat. The copper-quats worktogether to protect the lumber from a wide range of rot anddecay. Quats are fungicides that attack decay organisms.ACQ treated wood has been tested and found to haveperformance characteristics similar to wood treated withCCA. Preserve, Preserve Plus, and NatureWoodPreserves are brand names for ACQ pressure-treated wood.Preserve Plus is ACQ pressure-treated wood with a built-in water repellent. More types of wood treated with ACQis available.

    Copper Boron Azole (CBA). CBA is a copper-based preservative with an organic fungicide. The treatedwood is a dark honey brown color and turns a silver-gray

    after it weathers. The brown color can be restored bylightly sanding the outer layer. Wood products treated withCopper Azole have been used effectively around the worldsince 1992. Copper Azole is a fixed preservative approvedfor full exposure to above ground, ground contact andfreshwater applications. It provides long-term resistance

    to termites and fungal decay in ground contact andaboveground applications. CBA treated wood can be usedfor most applications where CCA is used such as decks,walkways, gazebos, picnic tables, play structures, etc. It isnot approved for wood foundations. Wolmanized NaturalSelect is a brand name for CBA-treated wood.

    Borates. Borates are also effective at protectingwood from decay under the right circumstances, howeverthey are very different chemicals. The copper-basedpreservatives chemically bond to the wood in otherwords, they are fixed in the wood and cannot diffusethroughout the piece nor can they wash out. This meanscopper-based treated wood can be used outdoors or even

    submerged in water. Borate, on the other hand, is diffusible in other words, it doesnt lock onto the wood like copper-based preservatives. The advantage of diffusion is boratesability to keep moving deeper into the wood after pressuretreatment. The disadvantage is that borate can leach out oftreated wood that is continuously exposed to water. Boratesare approved only for above-ground applications that arecontinuously protected from water, such as sill plates andother enclosed structural framing.

    How long will treated wood last? It depends on theuse and location. For best results, it is important that youuse a treatment level (retention) appropriate to the end

    use. Thus, for an above-ground application (e.g., flooring)0.25 per cubic foot ACQ is suitable. For ground-contactapplications, 0.40 per cubic foot ACQ is appropriate.

    A pplication R etention (lbs. /cu. ft. ) Uses

    A bove ground decking using

    Sapwood species (Southern pine,ponderosa pine, red pine, radiata

    pine, and car ibbean pine)

    0.15 + water repellent

    Decking, hand rails, spindles, trellises, gazebos,

    fence boardsA bove ground decking using

    Heartwood species (Douglas fir,western hemlock, hem-fir , lodgepolepine, jack pine and redwood)

    0.25 + water repellent

    A bove ground - general use 0.25Framing lumber, trim & fascia, flooring, sill

    plates

    Ground contact 0. 40Deck support posts, fence posts, landscaping,

    piers, docks

    C ritical structural members 0.60Permanent wood foundations, timbers, building

    poles

    Table 1. Minimum recommended ACQ retentions for various applications.

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    Preventing Termite Infestations

    Other Options

    Resistant Woods. Naturally resistant woodsinclude redwood, cypress and cedar. These woods aresomewhat resistant to termites, although they are not asresistant as treated lumber. For maximum termite and

    rot resistance, it is important to use the heartwood whereresistant compounds are concentrated. Constructioncommon grade wood contains sapwood and, like anynondurable wood, would only last a few years with groundcontact.

    Plastic and Composite Materials. Thereare two types of lumber products made from recycledplastic. One is 100% plastic. The other type is a compositematerial made from recycled plastic and waste wood fiber,like sawdust.

    Unlike traditional lumber, plastic and wood compositelumber needs no maintenance or sealing. Plastic lumberdoes not splinter, rot, chip or warp and is impervious to

    insects. Like wood products, it can be sanded and fastenedusing traditional tools and methods. Plastic lumber iscommonly available in three grades, hollow, solid, andstructural solid. Hollow grade plastic lumber can be usedfor light-load applications such as low-load deck surfaces,fences, and shutters. Regular solid grade plastic lumbercan be used for medium-to-light load applications, such asdeck surfaces and planters. Structural grade plastic lumberhas a 20% fill of fiberglass to provide superior strength andreduce the expansion and contraction properties.

    Composite products have guarantees ranging from10 to 50 years. Even though plastic wood may cost

    more initially than traditional wood, there can be longterm savings due because of the low maintenance andlongevity.

    Termite Shields. Metal termite shields are morecommon in the southern U.S. where there is a higherlikelihood of termite infestation. Termite shields arenot used very often in northern climates but could beinstalled by home builders. These shields will not protecta structure from termites but, whenproperly installed, force termites totube around them and make tubingmore evident. They would be veryexpensive to install in existing

    structures.Termite shields are sheets of a

    non-corroding metal placed betweenthe concrete or solid masonry wallsand structural wood. To be properlyinstalled, lengths of metal should becarefully overlapped and soldered orriveted to form a continuous shieldaround the foundation. It should beemphasized that termite shields willnot protect a structure from termites

    but force termites to tube around them where the tubeswill be more visible. To be useful, regular inspections areneeded and additional control methods may be needed.

    Sand (or crushed stone) Barriers. In the late 1950stwo researchers discovered that subterranean termiteswere unable to tunnel through sand of a specific particle

    size. This discovery suggested that surrounding a structurewith sand could prevent termite entry into a home. Sandor crushed stone barriers can be applied in crawl spacesunder slab foundations, and next to foundation walls.

    However, not just any sand or crushed stone wilprevent termites. The size of the sand or crushed stoneparticles is critical to the success of a barrier. Sand/crushed stone size should be no larger or smaller than thatable to sift through a 16-mesh screen. Particles smallerthan 16-grit can be carried away by termite workers; largerparticles can support tube construction. Sand or crushedstone barriers are routinely done on new constructionin Australia and Hawaii. In the continental U.S., some

    companies in California are providing treatments, but thisnovel treatment has not been used much in the rest of theU.S.

    Stainless Steel Mesh. Another physical barrier isstainless-steel wire mesh. Research has shown it is extremelyeffective, even in very high termite areas. Currently acompany in Australia is marketing mesh (0.45 mm x 0.86mm) in 100-foot stainless steel wire rolls and used duringbuilding construction. It can be shaped and fitted aroundpipes, posts, foundations and trenches. Because of cost, ithas limited utility in post construction applications andwill probably be used mainly in custom-built homes.

    Steel Studs. Steel studs used during new constructionor remodeling can help reduce the risk of termiteinfestation. If the walls contain metal instead of woodenstuds, the termites cant damage them. However, termitescan build mud tubes on the metal studs to gain access towood in other parts of the house.

    Concrete home. One of the latest trends in new homeconstruction is the use of concrete. Not only is the concrete

    used for basement walls and foundationsbut it is now being used in whole housewall, ceiling, floor, and roof constructionThe poured concrete house comes veryclose to a termite proof home. Keep

    in mind that if any wood in used in theconstruction of the house and if termiteare in the soil surrounding the house, thetermites can potentially find the wood.

    Figure 4-4. Termite shield overuncapped masonry wall.

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    Termiticides: Termite Control Chemicals

    Chapter 5

    Termiticides: Termite Control

    ChemicalsWhat is a chemical? Everything around us, the earth,

    air, even our bodies are composed of chemicals. Thesmallest part of a chemical is called an atom. When atomsexist in a pure state, the substance is called an element.Oxygen, hydrogen, nitrogen, and carbon are some of themost common elements. When two or more elements arecombined chemically, they are called compounds. Water,a common compound, has two hydrogen atoms and oneoxygen atom (hence, H

    20).

    Animals and plants are composed of chemicals; mostof which are very complicated chemical compounds. Thechemistry of living things is known as organic chemistrybecause they are composed primarily of the organicelements carbon, hydrogen and oxygen. To some people,the word organic means that something is natural orgrown in the absence of synthetic fertilizers and pesticides.For our purposes, organic refers to a chemical compoundcontaining the organic elements.

    Pesticides are chemicals that either control pests orprevent the pests from causing damage or infesting anarea. If the pest is a weed, we use a herbicide; if it controls

    rodents, it is called a rodenticide. Fungicides controlfungi, insecticides control insects, and termiticides controltermites. Most termiticides are organic compounds thatare synthesized by chemists and manufactured by chemicalcompanies. There are a few, however, that are made fromplants, minerals or non-organic elements that have theability to control termites.

    Termiticide FormulationsAn active ingredient is the specific chemical in a

    pesticide product that does the dirty work. An activeingredient is mixed with less toxic inert ingredients. The

    mixture of active and inert ingredients is called a pesticideformulation. The directions on the label tell the applicatorhow to use a pesticide formulation. Since control is oftenbased on how the termiticide is used, a homeowner who isinterested in having an effective treatment should read andunderstand the label directions.

    There are a number of termiticide products thatare labeled for termite control in and around homes,apartments, and dwellings. In this section, we will describethe formulations that are used for termite control.

    Liquid Formulations

    Emulsifiable Concentrates (EC). Emulsifiableconcentrates are uniform mixtures of the concentratedactive ingredient, oil-based ingredients and otheringredients. When the EC is diluted in water, the activeingredient and oil droplets are suspended uniformlythroughout the water. ECs are normally opaque or milkyin appearance. Emulsifiable concentrates can be toxic to

    plants and are easily absorbed through the skin. Certainoil-based ingredients that are used with EC formulationscause the strong smell that we often associate withpesticides.

    Many of the termiticides labeled for chemical barriertreatments are emulsifiable concentrates. They are usuallyeither organophosphates or synthetic pyrethroids. See therelevant sections in this chapter and Appendix A for moredetails.

    These termiticides are also labeled for surfaceapplications to wood for controlling termites and otherwood destroying insects. Soil barrier treatments and wood

    treatments are discussed in detail in Chapter 6.Water Miscible Liquids. Liquid miscible liquidsare mixable in water. The concentrated active ingredientis able to dissolve in water or alcohol. These formulationsresemble ECs but do not become milky when diluted withwater. Water-miscible liquids are labeled as water-solubleconcentrates (WSC), liquids (L), soluble concentrates (SC)or solutions (S). An example of a termite control productthat is a water miscible liquid is Bora-Care, a boric acidproduct used to treat wood.

    Dry Formulations

    Dusts (D). Dust formulations contain an activeingredient plus a powdered dry inert substance like talcclay, nut hulls, or volcanic ash. The inert ingredientsallow the dust formulation to store and handle well. Inthe home, dusts should be used only in locations wherethe inhabitants will not stir the dust, move it around, orinhale it.

    Wettable Powders (WP or W). These aredry, finely ground, powdery formulations. They look likedusts, but a wetting agent has been added to the other

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    ingredients to help them to mix with water. Wettablepowders form a uniform mixture of particles rather thanbecoming dissolved when added to water. A wettablepowder formulation registered for termite control as abarrier treatment is Premise 75 (imidacloprid).

    Baits (B). A bait formulation is an edible or

    attractive substance mixed with a toxicant. When baitsare used against termites and other social insects, the mosteffective baits will contain active ingredients that have lowtoxicity and cannot be detected by the foraging insects.It is important that a lethal dosage of the bait toxicantis passed throughout the colony to affect all the colonymembers. Since termites eat cellulose, paper is often usedas the carrier for termite baits.

    In 1994, Dow AgroSciences received EPA registrationfor hexaflumuron, an insect growth regulator. Since then,there have been several additional bait products thathave been registered for termite control. In 1996, FMCintroduced FirstLine, a bait that uses sulfluramid as its

    active ingredient. In 1998, Exterra Termite Interceptionand Baiting System was registered by Ensystex, Inc. Thebait ingredient of this system is diflubenzuron (commonlycalled Labyrinth), another insect growth regulator. Themost recent ingredient to be registered is noviflumuron,also by Dow AgroSciences. You can be sure that there willbe many more baits appearing on the market over the nextseveral years. Bait products will be discussed in detail inChapter 7.

    Miscellaneous Formulations.There is anothertermite product that has an unusual formulation. Jectais a borate that is formulated as a gel to be applied with

    a syringe into cracks of wood. More information aboutborates is found later in this chapter.Foaming Agents. Foams may be used as part

    of a chemical barrier treatment to help distribute thetermiticide in areas that might be difficult to treat. Foamresults when air is forced into the termiticide mixed witha foaming agent.

    The use of foaming agents is a developing technology intermite control. The foam is a compact mass of air bubblesseparated from each other by a liquid film; air makes upabout 85 percent to 95 percent of the foam. There are wetand dry foams depending on how much water is used inthe mix. After a few minutes to hours after application, the

    foam breaks down into a liquid as the bubbles collapse.The foam helps distribute insecticide in areas that

    are difficult to treat, such as under slabs and outsidesteps, around rubble foundations, behind veneers, andin voids found in walls, chimneys, and masonry. Most ofthese sites are treated blindly. Foams will disperse aroundobstructions and will better fill a void. Once the foam hasspread into the desired area, the solution drains from themass of bubbles downward into the fill. This can will resultin a more complete, uninterrupted treatment barrier.

    Termiticide Classes

    Chlorinated Hydrocarbons: Banned A fewof the better known chlorinated hydrocarbons are DDT,aldrin, dieldrin, heptachlor, and chlordane. Throughoutthe 1970s and 80s, the EPA banned most chlorinated

    hydrocarbons in the United States because these insecticidespersisted in the environment and accumulated in the fattytissues of animals. The last chlorinated hydrocarbon to beused for termite control was Chlordane. Chlordane waswithdrawn from the market by its manufacturer in 1988.It persists in the soil so long that there still may be housesprotected from termites by a chlordane treatment that wasdone before 1988. These insecticides should not be used intermite control.

    Organophosphates (OPs): OPs are generallymore toxic to vertebrates (including humans) than thechlorinated hydrocarbons, but they are much less persistentin the environment. Until recently, chlorpyrifos was used

    extensively for termite application. Chlorpyrifos barriersare non-repellent to termites and kill termites quickly oncontact. This action results in many dead termites near thepoint of contact with the barrier. It is thought that the deadtermites deter other termites from the treatment zone.

    However, the Environmental Protection Agencyrevised the risk assessment for chlorpyrifos and reachedan agreement with the registrants to eliminate and phaseout certain uses of chlorpyrifos. All uses of termiticideformulations containing chlorpyrifos have been phasedout.

    Botanicals: Naturally Occurring. Botanicals

    are natural insecticides, made from plant extracts. Whenprocessed and concentrated, these botanical insecticidesare similar to synthetic insecticides. Some people believethat natural-occurring botanicals are safer to use thansynthetic insecticides. This is not necessarily the case.Nicotine sulfate, a botanical derived from tobacco plants,is more toxic to mammals than many other syntheticinsecticides.

    A botanical insecticide used to control some insectsis pyrethrum, a natural compound that comes from thechrysanthemum plant. Pyrethrum has low toxicity tomammals but causes very fast knockdown and rapidparalysis in the target insects. Because pyrethrum breaks

    down very quickly in the environment, it is not very usefulas a termiticide.

    To increase the effectiveness of pyrethrum, chemistshave synthesized similar, more stable compounds in thelaboratory. These laboratory-created insecticides areknown as the synthetic pyrethroids and a number of thesechemicals are long-lasting enough to be useful for termitecontrol.

    Synthetic Pyrethroids. Dozens of syntheticpyrethroids have been identified and synthesized. A few

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    used in termite control include fenvalerate, permethrin,cypermethrin and deltamethrin. (Notice the thrinpart of the name of many of these common names.)Chemists have made these compounds more stable andmore persistent than natural pyrethrum. A chemical,like piperonyl butoxide, is often added to the synthetic

    pyrethroid to further increase its effectiveness.When used against termites, synthetic pyrethroids are

    highly repellent but kill very few termites. Instead, termitesavoid the areas where these chemicals have been applied.Pyrethroids are very toxic to fish so precautions must betaken to prevent these chemicals from getting into streamsand other surface waters.

    Compared with some formulations, there is lessodor associated with synthetic pyrethroids, and they maybe preferred for inside treatments, like drilling throughslabs or basement walls. Even though the odor may beless, the solvents in synthetic pyrethroids sometimestrigger asthmatic attacks in persons who have respiratory

    problems.Chloronicotinyls. This class of non-repellent

    termiticides was introduced in 1996 when Premise75 became available as a barrier treatment. The activeingredient of Premise 75 is imidacloprid, which acts byattaching to specific binding sites at the nerve endings oftermites. Because warmblooded animals have fewer ofthese receptor sites, imidacloprid has a very low toxicityto mammals, when compared with organophosphates andsynthetic pyrethroid products.

    Unlike synthetic pyrethroids, that are readily detectedin the soil, termites do not detect imidacloprid and tunnel

    into treated soil. After contacting imidacloprid, termitessoon stop feeding, become disoriented, and eventuallydie. The termites exposed to lower concentrations ofimidacloprid are left susceptible to naturally occurringpathogens in the soil and later die from diseases.

    Phenyl pyrazoles. This is a new class of non-repellent termiticide. Fipronil was made available as atermiticide during 2000. After five years of testing, resultsindicated that fipronil provided 100 percent protectionagainst termite attack at several USDA field testinglocations in the United States. This active ingredient is soldunder the name Termidor.

    Pyrroles. Chlorfenapyr is a slow acting, non-

    repellent termiticide. The slow acting action allows timefor the termites to transfer the chlorfenapyr to other colonymembers. It was introduced into the termiticide marketin 2002 as Phantom. Termites pick up chlorfenapyr viaingestion and through contact. The activity via the oralroute is excellent, and the contact activity is roughly equalto that of organophosphates. The mode of action is novelamong termiticides. After chlorfenapyr enters the termite,it keeps the termite from generating its own energy. As aresult, the exposed insect will die.

    Fluoroaliphatic Sulfonamides. The fluo-roaliphatic sulfonamides are relatively new, especially astermiticides. Sulfluramid is a slow-acting stomach poisonThere are two termiticide products containing sulfluramidFirstLine Termite Bait Stations (FMC Corp.) and Termi-nate (Spectracide Corp). Both products are formulated

    as termite baits. Sulfluramid use results in termite colonysuppression, not colony elimination.

    Trifluoromethyl aminohydrazones. Hydra-methylnon is the active ingredient in a termite bait systemcalled Subterfuge. Hydramethylnon acts to inhibit theproduction of energy inside the insect. Insects killed bythese chemicals die on their feet, basically running out ofgas.

    Hydramethylnon has a relatively low toxicity tomammals. When hydramethylnon is eaten, the termitecolony is suppressed. The speed that the colony issuppressed depends on the amount of bait that is eaten.

    Inorganics.Borates. There are several products labeled for termite

    control that have a compounds containing boron as theiractive ingredient. Boric acid and disodium octaboratetetrahydrate are chemical forms of boron. The borates areused to treat the surface of wood, either as a preventativeor remedial treatment. These products work because theborate penetrates wood and is ingested by termites asthey attempt to eat the wood. Boric acid has been knownto successfully kill insects for decades, but little is knownabout its mechanism of activity. The most acceptedhypothesis is that boron kills intestinal microorganismsthat allow insects to digest their food.

    Borates are formulated as a liquid (Bora-Care), or apowder (Tim-bor) that are mixed with water and appliedto the surface of wood. It is also formulated as a gel, Jectathat is injected with a syringe into posts, poles and highrisk areas through cracks in the wood or predrilled holesBorates have also been impregnated into rigid foam andfiberglass insulation products.

    MicrobialsNematodes. Insect-eating nematodes are tiny parasitic

    roundworms that naturally live in the soil. They are soldfor termite control. However, there is a problem when usingnematodes for termites control. In laboratory studies, thenematodes killed termites, but these results have not been

    repeated in conditions such as in a termite infested homeIn addition, applications of nematodes have not beenshown to prevent termite infestations.

    Based on the lack of effectiveness under real conditionsnematode products should not be considered a practicaleffective method of termite control.

    Pathogenic Fungi. Many species of fungi live in thesoil and some infect and kill insects that live there. Ithas been known for many years that a fungal pathogenMetarhizum anisopliae, naturally kills termites. This

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    pathogen has been studied extensively and is now marketedas a termiticide called BioBlast; however, this productis not currently registered for use in Nebraska. Infectionoccurs when the fungal spores germinate, penetrate thetermites body, and grow inside the body. Studies haveshown that this disease is highly infectious. After termites

    become infected, the spores are quickly spread to othercolony members. However, once termites start dying,noticeably sick termites are shunned by healthy termites.This behavior reduces the further spread of the disease.Studies have shown that if 10 percent of colony memberscan become infected initially, it is likely that the remaining90 percent of the colony will be infected.

    These pathogenic fungi are not applied as a barrier ora bait treatment. Instead, they are applied as a suspensionof fungal spore particles that act as a contact termiticide,except the infected termites dont die immediately. Itmust be applied so that it gets right onto the termites, not

    just their environment. For the whole colony to become

    infected and possibly eliminated, this pathogen mustbe applied to as many termites as possible. When usedcorrectly, this pathogen can be very effective to controltermite colonies that are colonizing the wood itself, suchas some drywood species.

    At the present time, the Metarhizum anisopliaepathogen is less likely to effectively control subterraneantermites because it is nearly impossible to infect enoughforaging termites to get the infection started. A secondproblem is that it has no long-lasting residual activity. Afterthe termites die, the fungal spores also die. In addition, thispathogen is not like anything else available on the market

    and needs special application and handling techniques.It needs to be stored properly and will not be effective iftank-mixed with insecticides. This fungi pathogen hasits best chances of use in subterranean termite control,when used in conjunction with baiting programs applieddirectly to foraging termites, or in sensitive environmentswhere more toxic chemical treatments cannot be used.

    Insect Growth RegulatorsInsect growth regulators are a group of compounds

    that alter growth and development of termites and otherinsects. They are much less toxic to humans and othernontarget organisms than the majority of termiticides.These synthetic biochemicals cause abnormal growth

    and/or development and either kill the termite outrightor prevent it from reproducing. This group of termiticidesare most often used in termite baiting technologies, to bediscussed in Chapter 7. Hexaflumuron and noviflumuron(Sentricon) and diflubenzuron (Exterra and Advance)are two IGRs currently registered by the EPA and labeledfor termite control. All belong to the group of IGRsthat are called Chitin Synthesis Inhibitors, which meansthat they inhibit the growth of chitin, which is the maincomponent of the insect exoskeleton (insect skin or

    shell). Because only insects, other arthropods and fungicontain chitin, these hormone mimics are more specificto insects than other termiticide treatments that effectthe nervous system, for example. This makes them moreenvironmentally friendly and safer for humans and othernontarget animals.

    Repellency vs. Non-repellencyTermites are affected differently by termiticides,

    depending upon the way the termiticides are applied (soil,surface of the wood, bait), and by the unique characteristicsof each termiticide class or group. Soil-applied termiticidesare designed to provide a protective barrier between thetermites and your house. You might wonder if it is best touse a repellent or a non-repellent liquid barrier termiticide.Chloronicotinyls, phenyl pyrazoles, and pyrroles arerelatively new non-repellent to the termite termiticidescompared to the older synthetic pyrethroids that are highlyrepellent to termites. Research evidence has accumulatedover the last several years indicating that the newer non-

    repellent termiticides are more effective than repellenttermiticides at protecting your home from termites.

    Non-repellent termiticides are not detected bytermites. Because they dont know its there, the termiteworkers forage freely in the treated soil. However, becausenon-repellents are slower to kill and termites that contactthe chemical in the soil carry it back to the colony ontheir bodies. Every other termite that the original termitetouches will itself become infected. This is known as theso called transfer effect or domino effect. Because thesenewer non-repellent termiticides are lethal to termites atvery low doses, the transfer from contaminated termites

    to clean termites can result in the eventual weakening orelimination of the colony.Termiticide TestingAll soil applied termiticides must pass a two-step

    process before EPA will register the product. Compoundsare first screened in the laboratory, and from among thosetested in the lab, only a very few ever make it to fieldtesting. Field testing is done at testing facilities in Arizona,Florida, Mississippi, and South Carolina. The test sitesrepresent dry, subtropical, and mild climates, as well asdifferent soil types. These field testing locations representa worst case scenario for the termiticide. If it can provideprotection against termites under these conditions, it is

    a good indication that it will also perform well in mostother conditions across the United States. Termiticidesare evaluated for as long as they remain effective againstsubterranean termites. These tests provide the informationnecessary to register and label soil termiticides in the U.S.A summary of these tests is provided at the end of chapter6.

    Unlike chemicals used for barrier treatments, baits havenot had rigorous testing to determine their effectiveness.Since there are no performance guidelines, at the present,

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    persons should be somewhat skeptical regarding claimsmade about these bait products. In the future, performancecriteria will be established for both new and existing baitproducts and products lacking performance data will berequired to generate additional data and/or adjust theirclaims. In the meantime, be cautious about outlandish

    claims that seem to be too good to be true.

    How Long Do They Last?Recent studies have shown that all registered soil

    applied termiticides disappear over time. In one extensivestudy, it was found that after 5 years less than 10 percent of

    the initial application rate remains. The loss of termiticidein soil could be the result of individual peculiarities at eachtreatment site. Evidence indicates that some microbes eattermiticides, which could explain part of the disappearance.Some termiticides disappear because chemical reactions inthe soil break the termiticide molecules into smaller, less

    effective pieces. S