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Home , Termite

E-368 12/05

Subterranean Roger E. Gold, Harry N. Howell Jr., Grady J. Glenn and Kimberly M. Engler*

ubterranean termites are the most state. Overall, termites are consid- destructive pests of in the ered the most economically important because S United States. They cause billions of dol- they are so broadly distributed. lars in damage each year and have a negative The second and increasingly important ter- impact on a family’s most valuable possession— mite is the introduced Formosan subterranean the home. , formosanus. The Formosan In nature, subterranean termites are beneficial termite is easily transported from one infested because they break down into usable area to another in landscape timbers, railroad nutrients. The resulting from this cross-timbers, mulch and wooden pallets. process is recycled to the soil as . Isolated infestations of Formosan termites have Subterranean termites are, therefore, considered been reported in many areas of the state (See E- important in our ecosystem. 367, “Formosan Subterranean Termites”). Problems occur when termites attack the wooden elements of homes, businesses and warehouses built by humans. The presence of Identification termites is often not readily noticed because their Subterranean termites are social that activity is hidden behind wallboards, siding or live in colonies within the soil, hence their wood trim. Homeowners in all areas of Texas name “subterranean.” These colonies contain should watch for subterranean termites and take three forms or castes: reproductives, workers precautions against infestations. To minimize (pseudergates) and soldiers. Subterranean ter- damage from termites, it is helpful to know the mites have several stages: the , larva, apter- description, life cycle and signs of infestation of ous workers (wingless), a brachypterous termites as well as preventive and control mea- (with wing pads), soldiers and adult swarmers. sures. There are three forms of adult reproductive ter- mites including primary, secondary and tertiary Distribution (Fig. 1a). Reproductive males and females can be Several of subterranean termites are winged (primary) or wingless (secondary or ter- found in the United States; they live in every tiary). Females of each can lay and pro- state except Alaska. Two major types of subter- duce new offspring. The bodies of winged pri- ranean termites are commonly found in Texas. mary reproductives, also called swarmers or They are the native subterranean termite and alates, vary by species from coal black to pale Formosan subterranean termite, and both are yellow-brown. Wings may be pale or smoky serious threats to wooden structures. gray to brown and have distinct vein patterns Native subterranean termite species in the used in identification. Reticulitermes swarmer 1 3 Genus Reticulitermes are found throughout the termites are about ⁄4 to ⁄8 inch long. Secondary and tertiary reproductives live *Professor and Extension Specialist in Urban ; within the colony and are white to cream-col- Associate Research Scientist; Research Associate; and Program ored. These termites form a backup for the pri- Specialist—Urban IPM; The Texas A&M University System. mary queen and may replace her if she is injured or dies. These termites mate within the Figure 1a. Swarmers, winged reproductives colony and lay viable eggs. If supplementary reproductives and worker termites become iso- lated from the main colony, they can establish a new sub-colony. Termite workers make up the largest number of individuals within a colony and do all the work. They are wingless, white to creamy 1 3 white and ⁄4 to ⁄8 inch long (Fig. 1b). They for- age for food, feed the other castes, groom the queen and maintain and build tunnels and shelter tubes. Their mouthparts are very hard and adapted for chewing through wood or Figure 1b. Workers other cellulose materials. The worker caste is responsible for the damage that makes termites an economically important problem. Soldiers resemble workers in color and gener- al appearance, except they have well-developed brownish heads with strong mandibles or jaws (Fig.1c). Soldiers defend the colony against inva- ders, primarily and other termites. They cannot forage for food or feed themselves, and they depend on the workers to care for them. Ants and termites often swarm at about the same time of year but control measures for each differ greatly. It is therefore, important to Figure 1c. Soldier be able to distinguish between swarming ter- mites and ants. (Fig. 2). Biology and habits After 2 to 4 years a subterranean termite colony is mature and produces “swarmers” (winged primary reproductives). Termite swarm- ers leave the colony in large numbers during the spring and early summer. Swarming begins in Figure 1. Subterranean Termites. South Texas in January and February; in the

Antennae elbowed Antennae not elbowed

No wing stub Stubs left when wing detaches

Middle part of body Middle part of body very narrow Wings not alike in Wings similar in shape, size, or not narrow shape, size, and pattern – few veins pattern – many small veins Termite Figure 2. Differences between ants and termites.

2 Panhandle region of Texas, swarms do not occur remains with the female and helps care for until April and May. Environmental factors such developing eggs and the larva that hatch. as heat, light and moisture trigger the emer- Eggs are not deposited continuously. In fact, gence of swarmers, with each species having its only a few hundred are deposited during the own set of requirements. The number of swarm- first year. As the young queen grows larger, ers produced is proportional to the age and size she lays more eggs. The king and queen care of the colony. A summary of termite biology is for the young larvae that hatch from the eggs shown in Figure 3. because they cannot care for themselves. The Both male and female swarmers fly from the larvae then molt into pseudergate workers, colony and travel short distances. Termites are which, in turn, can molt into presoldiers or weak fliers and must rely on wind currents to brachypterous nymphs (with wing pads). carry them to new habitats. Only a small per- These nymphs will eventually molt to become centage of swarmers survive to develop primary reproductives. The colony stabilizes colonies; most fall prey to , toads, insects when the queen reaches her maximum egg and other predators, and many die from dehy- production. If the queen dies, supplemental dration or injury. reproductives take over the queen’s duties. During the swarming process, males (kings) The maximum size of a termite colony and females (queens) pair off using phero- depends on location, food availability and mones. Successful reproductive pairs land, lose environmental conditions, especially tempera- their wings and seek cover under rocks or ture and moisture. Some colonies remain other moist materials. A pair will make a very small; others contain up to several thousand small before mating. Initially, the new individuals. New colonies form when the old queen termite lays only a few eggs. The male colony produces swarmers or when groups of

Pseudergate "worker" Larva

Pseudergate Nymph Soldier "worker"

Presoldier 3rd form reproductive 2nd form reproductive

Alate "swarmer" (male or female)

Primary reproductives

Larva King (male)

Egg

Queen (female) Figure 3. Native subterranean termite life cycle.

3 termites become isolated from the main colony ed or can be large with thick walls to accom- and establish sub-colonies. This is called modate many termites moving vertically “colony splitting” or “budding.” These sub- between the soil and their food source. colonies may exist independently or reunite Subterranean termites also transport moist with the main colony. soil into the structures they infest. The presence Subterranean termites get their nutrition of shelter tubes and mud within galleries is from wood and other material containing cellu- used to identify termite-damaged wood (Fig. 5). lose. Paper, cotton, burlap or other plant prod- Shelter tubes are often used to bridge across ucts often are actively consumed by termites. masonry or other objects, allowing termites Sometimes termites will even tunnel into the access to a food source (wood) above ground. dead heartwood or pith of living plants. Most Inspecting of structures for termite damage may species of subterranean termites cannot digest identify these tubes which indicate an ongoing cellulose directly and depend on single-celled infestation. protozoans and living in their hindguts to help digest the cellulose. Digested cellulose is then shared with the developing larvae, Damage other workers, soldiers and reproductives. Dead trees and brush provide a natural food Termites are attracted to certain odors of source for subterranean termites. wood-decaying fungi that make the wood more When natural vegetation is cleared and houses palatable and easier to penetrate. In some are built, termites often switch to feeding on instances, the fungi provide a source of nitro- wooden structures. Termites enter buildings gen in the termite diet. through wood that is in direct contact with the soil and by building shelter tubes over or Moisture is important to subterranean ter- through cracks in foundations. Any cellulose mites as they have very little resistance to material in direct contact with the soil, such as dehydration. To survive, termites must main- trees, vines or plumbing fixtures, can serve as tain contact with the soil (their primary mois- an avenue of infestation. ture source) or other above-ground moisture sources, such as defective plumbing, leaky Signs of infestation roofs, leaks from air conditioning condensers Active termite infestations can be difficult to or poorly maintained gutters. detect. To find out if a home is infested, the Subterranean termites also must protect structure should be checked for evidence of themselves from temperature extremes and swarmers (including wings or dead termites in attack by ants and other insects. Termites that windows), mud tubes or damaged wood inside forage for food above ground protect them- or around a structure. selves with shelter tubes or “mud tubes” (Figs. 4a and b). Worker termites build shelter tubes from particles of soil or wood and bits of Stud debris held together by salivary and fecal secretions. Mud tubes may be thinly construct- Wallboard Baseboard Flooring

Subfloor Termite tubes Joist

Beam

Nest Figure 4a. Termite shelter tubes on foundation wall. Figure 4b. Typical termite shelter tubes.

4 soft fecal material plastered on tunnel surfaces. Moisture sources may cause wood decay and can encourage subterranean termite infestation. Deterioration caused by wood-destroying fungi can be confused with termite damage. Other insects attack wood, and their appear- ance or the nature of their damage varies widely. For more information, refer to E-366, “Drywood Termites”; E-367, “Formosan Subterranean Termites”; L-1783, “Carpenter Ants”; L-1826, “Carpenter ”; and L-1784, “Wood Destroying .” Figure 5. Typical wood damage by subterranean termites. Management Swarmers: Generally, the first sign of infes- Control measures include reducing the poten- tation homeowners notice is swarming repro- tial for subterranean termite infestation, pre- ductives on windowsills or near indoor lights venting entry, using termite bait and applying (Fig. 1a). Swarming termites inside the house residual chemicals for preventive or remedial usually indicate an active infestation in the treatment. structure. Termite wings may be found on win- dowsills or stuck to cobwebs indoors. Though Inspection swarmers outdoors are a natural phenomenon, Although it is possible for a homeowner or they indicate that termites are present and may property manager to perform an inspection, it is be attacking nearby structures. recommended that licensed professional inspec- Mud tubes: Mud shelter tubes on crawl tors do this work. They should be familiar with space piers, utility penetrations or on founda- termite biology and habits as well as construc- tion walls and slabs are a sign of termite infes- tion methods and conditions that are conducive tation. Termite shelter tubes can blend in well to termite attack and infestation. control with the soil or concrete, making them difficult professionals can determine the presence of to see. To make inspecting the home for ter- infestations and damage, the need for remedial mites easier, prune vegetation away from house control measures and the measures to use to walls. The soil line should be several inches eliminate the conditions that encourage termite below the top of slabs or foundation walls. An attacks. inspector should look for mud tubes carefully and equipment needed for an inspection along foundation walls and slabs, especially include a flashlight, ice pick or sharp-pointed along cracks, in corners or where the top of the screwdriver, ladder and protective clothing foundation is close to the ground. A screwdriv- (bump cap, coveralls, rubber knee pads). A clip- er is useful to break open suspected termite board, graph paper and floor plan or sketch help tubes and detect live termites. in recording inspection findings accurately and Damaged wood: Wood damage often is not ensuring that the entire structure has been exam- found initially, but is positive indiction of a cur- ined. A moisture meter can often detect moisture rent or past termite infestation. Wherever wood levels in walls that encourage subterranean ter- comes in contact with the soil there is a high mite infestations. Motion detectors, x-ray tech- risk for termite entry. Carefully examine any nology, acoustical detectors, infra-red cameras wood that thuds or sounds dull when struck by and fiber optic boroscopes are also available for a screwdriver or hammer. Probing suspected termite inspections. areas with a sharp instrument such as a screw- Where to check outside. driver or an ice pick will often disclose termite galleries or damage. It is recommended that professional inspec- tors do the following when looking for termite Characteristics of damaged wood infestations: Subterranean termite damage is usually con- •Examine the foundation of the house, fined to the soft, spring-growth of wood (Fig. garage and other structures for shelter tubes 5). Termite tunnels and galleries tend to follow coming from the soil (Fig. 4a and b). Make the wood grain and are lined with mud or may note of any cracks or foundation damage have a pale, spotted appearance resulting from through which termites might enter.

5 •Report any places around the foundation larly in bathrooms on slab construction. If where soil extends above the top of the no access to the bath trap area exists, foundation, including built-in planter install a removable plumbing hatch and boxes with soil grades above the brick or periodically check the trap for termite stucco line. Pay special attention to shelter tubes. attached porches, connecting patios, side- •Examine the attic for shelter tubes, water walks, areas near kitchens or bathrooms leakage, wood rot or damaged wood. and narrowly confined or hard-to-see places. Note any area where inspections • If the house is of pier and beam construc- cannot be made. tion, inspect the area between the floor and the soil (crawl space) (Fig. 6). Examine the • Check the soil around or under the foun- inside of the beams, chimney bases, hearths dation to determine if faulty grade con- or piers for shelter tubes. The crawl space struction creates moist areas next to the should have a minimum 18-inch clearance structure. Irrigating the soil around the between floor joists and the soil, and at foundation may help prevent the slab least 12 inches between floor beams and from cracking, but it can also attract for- the soil. aging termites. Check windows and door- frames and where utilities (air condition- • Look under and around earth-filled porches, ing pipes, gas and electric services) enter patios, planters and bathrooms for water the structure for termites or wood decay. leakage and termite damage. If water stands underneath the house, take action to control • Check roof eaves and gutters for defects this moisture. that might cause leakage and eventual wood rot. Inspect behind closely planted, • Look carefully at the top of the foundation dense shrubbery or foliage. wall where the floor and the wall intersect. • Note any earth-to-wood contact such as • Closely examine plumbing and utility lines fences, stair carriages or trellises. passing through the floor of foundation walls. • Open and examine any exterior electrical Prevention meter or fuse box set into the walls, a Many termite problems can be prevented common point for infestation. through sound initial designs, mechanical alter- • Carefully inspect wood materials next to ations and good construction sanitation. The swimming pools that may be splashed basic premise behind prevention is to deny ter- frequently by water. mites access to food (wood), moisture and shelter. On the inside, the inspector should: Planning before construction is vital. Position or modify the building site so that the soil grade • Probe or carefully sound exterior porches, slopes away from the structure in all directions. doors and window facings, baseboards, Existing homes may need remedial grading or and hardwood flooring. Be careful not to deface finished wood when probing. • Check for unusual moisture levels and signs of infestation around earth-filled porches or other termite-prone features. Check ceilings for water damage (con- ducive conditions). •Examine all cracks or expansion joints in the foundation and any unusual blistering in paint or wallboard surfaces. Discolora- tion or staining on walls or ceilings may indicate water leaks that can decay wood Crawl space and aid termite infestations. Inspect where plumbing or utility pipes enter the foundation or flooring. • Check floor coverings for raised or split areas. • Carefully examine the plumbing, particu- Figure 6. Construction showing crawl space.

6 installation of positive drain lines. Soil-filled wood that will be in contact with the soil. Rest porches, patios, sidewalks or breezeways should wood porches, steps and stair carriages on solid slope away from the house. concrete bases to separate them from the soil Soil-filled porches and planter boxes should by at least 6 inches. Seal and caulk all founda- be removed from the house. Planter boxes tion openings, such as for plumbing penetra- should be built so that termites cannot enter tions and service utilities. Remove extraneous from the soil beneath. The soil in the planter cellulose material, such as form stakes, wood boxes should be at least 6 to 8 inches below any scraps or stumps, from underneath and around wooden structure such as sill plates, window foundations during and after construction. frames or siding. Stainless steel mesh or plastic sheeting Eliminate all wood-to-soil contacts, including impregnated with a termiticide is available for attached fence posts, stair casings, trellises and long-term termite proofing of new homes. door facings. Remove these structures from the These are normally installed on top of the soil soil and set them on masonry blocks or replace and around plumbing penetrations before the them with pressure-treated wood. The soil level slab is poured to prevent subterranean termites should be at least 6 to 8 inches below the top of passing through cracks or around pipes to gain the foundation or wall covering. This clearance access to wood in the structure. To be fully does not prevent construction of shelter tubes effective, these products should be installed over the foundation, but it does allow for visual under the whole foundation and not just inspection. Avoid planting shrubbery and dense around plumbing penetrations. foliage close to the house, as this increases Chemical management humidity and hinders inspection of the founda- Subterranean termites usually attack struc- tion line. tures from the ground up; therefore, termiti- At least 70 percent of the crawl space soil cides applied to the soil can deter attacks for under pier and beam structures should be cov- several years. For complete protection, there ered with 6 mil polyethylene water barrier. This must be a complete chemical or physical barri- helps prevent moisture build-up in the sub- er between the structure and the soil. In exist- flooring. Place exterior foundation wall vents ing homes, this barrier must be placed wherev- opposite each other and close enough to the er there is a point of possible termite entry. corners of the foundation to provide cross flow Preconstruction treatments: Treating the ventilation and eliminate dead air spaces. The soil under a structure with chemicals before number and size of vent openings should pro- construction (pretreatment) can effectively pro- vide 1 square foot of ventilation for each 150 tect it for several years. These chemicals can be square feet of crawl space area. applied accurately during early phases of con- Wood exposed to rain should be pressure- struction and eliminate the need for drilling treated with preservatives. Pressure-treated injection holes in the slab at a later date. Insist wood should be used for sill plates and for any that the contractor or architect specify that a preconstruction application of termiticide be applied to the soil before the slab is poured. This is the one time in the life of a structure when the soil beneath the slab can be protected against termites. Treating only the plumbing penetrations is incomplete. A complete pre-treatment must include all of the soil under the slab as well as trenching and treating the outside perimeter after the final soil grade is established. Though termite baits have been approved in Texas for use in lieu of a pretreatment, this approach to structural pro- tection from termites is not recommended. Post-construction treatments: For treating existing homes, termiticides should be applied to the soil inside and outside foundation walls, Figure 7. Removing wood-to-soil contact to prevent termite around piers or other supports and around utili- entry. ty entrances (Figs. 6-10). In instances such as

7 concrete block or brick foundations, the ter- places, under slabs or in soil-filled porches, for miticide must be pressure-injected through drill example, liquid termiticides may not reach ter- holes into foundation walls. Extensive drilling mites on vertical or elevated surfaces. Foam and pressure injection are often necessary in versions of can fill void areas and slab foundations as well as under earth-filled reach these difficult locations. Foam applica- porches, around fireplaces and along adjacent tions require specialized equipment and added patios and sidewalks. There are several termiti- surfactants and may not be available through cide products registered for these uses, and the all termite control companies. label directions must be carefully followed. Foams are not well suited for treating soil Termites attempting to tunnel into an insecti- directly. Liquids can penetrate soil more effec- cide treated area will be either killed or repelled. tively and should be used principally to treat Repellent termiticides do not kill termites, they most homes. Foams, however, are useful in suc- turn them away. This may allow some termites cessfully treating void areas where liquid ter- to avoid treated areas, then locate and use gaps miticides are ineffective. in the treated zone. Repellent termiticides pro- Some pest management companies offer vide immediate protection for the structure, and borates for termite prevention and control. maintain protection for up to 5 years. Currently These inorganic termiticides can be effective available repellent termiticides include when used according to label directions but are deltamethrin (Suspend® SC), permethrin more effective when used in conjunction with (Dragnet® FT, Prelude®), cypermethrin (Previal® other treatments. FT, Demon® TC), and bifenthrin (Talstar®). Inaccessible soil beneath a structure can limit Some current insecticides being used for ter- the effectiveness of soil-applied liquid termiti- mite control are considered nonrepellent cides. In homes that have crawl spaces with lim- (lethal) to termites when applied at standard ited access, for example, it may not be possible use rates. These insecticides do not repel, but to treat all possible termite entry points. In other kill the termites directly, as they tunnel homes, termites may be entering through an through the treated area. Lethal insecticides unusual location, where termiticides are not include (Premise®), normally applied. In such cases termite baits (Termidor®), and chlorfenapyr (Phantom®) and may be a useful alternative to liquid termiti- thiamethoxam. These nonrepellent termiticides cides, or they can be used as a supplemental provide approximately 5 years of protection treatment. and are usually effective within a few days. Baiting treatments: Since the mid-1990s, Foam treatments. In some situations, liquid termite control baits have been available as an termiticides fail to reach termites or their forag- alternative to soil-applied liquid termiticides. ing tubes. In void areas in walls, around fire Today’s termite control providers may offer Pipe

Figure 10. Pipes and utility lines entering through walls and slabs are Figure 8. Slab house must be com- heavily treated. pletely insulated from the ground by treated soil.

Figure 9. Crawl space houses are treated only around the foundations and piers.

8 several choices of baiting systems. • Use less than liquid treatments. This method takes advantage of termite food • Allow occupants to stay home during their sharing behavior to introduce an insecticide application. into the colony. Worker termites feed on ter- Before purchasing a baiting treatment, ask mite baits and carry the digested cellulose and the termite control professional for documenta- termiticide back to the colony where they tion of the effectiveness of the bait product. regurgitate their stomach contents to feed other You should also clearly understand the time termites. This sustains the queen, brood and required for effective control and the costs other less mobile worker termites. Rather than associated with monitoring and treating with keeping termites from entering a structure, termite baits as stated in the contract. baits are designed to suppress termite colonies so that they are incapable of feeding on the Other termites: The treatments discussed in structure. this publication are for subterranean termites. Drywood termites must be treated by removing Baiting technology requires that the techni- infested wood, using spot treatments or by cian be familiar with termite biology and fumigation. For more on identification and con- behavior and diligently monitor the bait sta- trol of drywood termites, see E-366, “Drywood tions. Some baiting systems are advertised as Termites.” Formosan subterranean termites may “stand alone” treatments for termite control; also require different control techniques. For others are used in combination with liquid ter- more information, see E-367, “Formosan miticide applications. Control can take several Subterranean Termites.” months to more than a year. Using bait for con- trolling termites has advantages and disadvan- Do-it-yourself termite control: Termite tages over liquid termiticides. treatment requires specialized drills, pressure injectors, pressure-generating pumps and high Disadvantages include: capacity tanks. It is advisable, in most cases, to • The amount of time needed to stop the use specialists as they are familiar termite feeding on a structure. (Termites with construction principles and practices, have may not quickly find and ingest the bait). the necessary equipment and know termite • They affect only termites that feed on the biology and habits. The Texas Structural Pest baits or receive the termiticide through Control Board licenses and certifies these pro- shared feeding. fessionals for competence in treatment proce- dures that provide safe and effective control. • They provide no residual protection for a For more information on how to choose a pest structure. Once discontinued, termites will management professional to treat your home, return and feed on the structure unless see E-369, “How to Select a Termite Control conducive conditions are eliminated. Service.” • Not not all baits have been thoroughly The USER is always responsible for the tested for effectiveness. effects of residues on livestock and Advantages of baits are that they: crops, as well as problems that could arise from contamination of neighboring property. Always • Eliminate the need for drilling holes into read and follow carefully the instructions on slabs, sidewalks and patios. the container label.

9 We are indebted to Phillip J. Hamman, former Extension urban entomologist, for developing the earlier revision of this publication and to Harry Howell, Jr., who helped prepare the original manuscript of this publication.

The information given herein is for educational purposes only. Reference to trade names is made with the understanding that no discrimination is intended and no endorsement by the Texas AgriLife Extension Service is implied.

Produced by AgriLife Communications and Marketing, The Texas A&M University System Extension publications can be found on the Web at: http://AgriLifeBookstore.org. Visit Texas AgriLife Extension Service at http://AgriLifeExtension.tamu.edu.

Educational programs of the Texas AgriLife Extension Service are open to all people without regard to race, color, sex, disability, religion, age, or national origin. Issued in furtherance of Cooperative Extension Work in and Home Economics, Acts of Congress of May 8, 1914, as amended, and June 30, 1914, in cooperation with the United States Department of Agriculture. Edward G. Smith, Director, Texas AgriLife Extension Service, The Texas A&M University System. Revision