Low Impact Termite Management

In the United States there are four groups of termites of concern: subterranean (including the Formosan termite), drywood, dampwood and powderpost. Subterranean termites and drywood termites are the two general types. Subterranean termites "nest" in the soil and from there they can attack structures by building shelter tubes from the soil to the wood in structures. Subterranean termites cause more of the damage to homes and structures than drywood termites so will be my primary focus here. Termites will attack any material with cellulose, including wood, paper coated wall board, and paper (as in that treasured book collection that occupies the lower level of my home). Wood that is at least 30% water saturated provides enough moisture. Additionally, termites will find free-standing water such as condensation, rain or plumbing leaks and use this moisture as their main source for survival. Termites have been a part of the ecosystem for thousands of years and aid in the decomposition of wood, freeing the nutrients in the decaying material for reuse by other organisms. Termites rely on eating the cellulose found in wooden structures, furniture, stored food and paper. It is virtually impossible to reside anywhere in the United States without confronting termites at one point or another.

Subterranean termites are the common termite in most states, and live below ground in colonies. Mature termite colonies tend to be decentralized with numerous nesting and feeding locations, interconnected by underground tunnels. The size of a colony can vary from less than 10,000 termites occupying 100-200 square feet to millions of termites covering an area as large as a half an acre. In higher density residential areas, the colony or colonies responsible for damage may actually be located in a neighbor's yard, rather than beneath the house that is infested. This requires that termite treatment involve both in house treatment and creating an external perimeter control to push back the colony. One of the oldest and least toxic treatment of in house termites and other pests is boric acid which will shut down the termite's nervous system. The termite will go into "shock" and the boric acid will simultaneously dehydrate the termite.

The treatment options for termites are bating for control of the perimeter with spot treatment both inside and out and traditional chemical barriers. Physical barriers installed during construction are also possible. As a practical matter physical barriers cannot be effectively retrofitted. Prevention of termites should be part of the construction process. Building codes require in most locations require that a construction site be pretreated for termites. Proper construction techniques, such as isolating wood from the soil, elimination and prevention of moisture and the use of physical barriers such as crushed glass, basalt, granite, quartz or silica sand can prevent termite attack. Certainly, adoption of vigilant construction methods and the use of inert physical barriers can prevent termite penetration into the structure and can provide more permanent termite control than is possible with insecticide applications to the soil alone. Very few of us build our own homes and the inclusion of permanent physical termite barriers often does not make the list of desirable features.

The new technologies for termite control can be safer to use and potentially less harmful to the environment than relying only on pesticides alone. Termite baits use small amounts of insecticide to knock out populations of termites foraging in and around the structure. Some baits may even eradicate entire termite colonies. Various methods of termite baiting are used in various products. The Sentricon Colony Elimination System is a termite control system from Dow AgroSciences it is the oldest and most widely tested of the commercially available baiting systems. It is comprised of several slotted, sub-ground level cylinders containing wooden monitoring devices. When termite activity is detected in a particular unit, the monitoring insert is replaced with a special bait tube. The bait used is a chitin inhibiting chemical which prevents the termites from molting. The idea behind this baiting method is that foraging termites consume the bait and pass it along to others within the colony, eventually working its way up to the queen, thereby eliminating the colony.

Sentricon has been commercially available since 1996. Several university etymology departments have conducted field tests over the years in the termite hot spots of Hawaii and the southeast. Beginning in fall 1993, field studies were conducted with a prototype Sentricon system around three representative structures in Hawaii, each of which had a history of subterranean termite infestation and recurring problems. Application of the hexaflumuron baits which is the active ingredient in the Sentricon system eliminated all termite activity at these sites. Continued monitoring is very important, though. Several years later, termites were again found to be reinvading two of the locations, but using baits again eliminated the infestation. The University of Kentucky also performed independent research studies. They, too, found that the Sentricon® is an effective termite control option. Some of these studies involved structural that could not be controlled using conventional liquid methods, which require the application of hundreds of gallons of chemicals into the ground to create an unbroken wall of soil soaked with chemical.

The Sentricon Termite Colony Elimination System was developed by Dow AgroSciences (Indianapolis, IN), and is sold only through authorized pest control firms. Termite control is not a DIY project. The bait contains a slow-acting ingredient, hexaflumuron that works by stopping the insect’s growth. It interferes with chitin synthesis, which termites need to form a new exoskeleton. Hexaflumuron has low toxicity and low mobility in the soil. It binds strongly to soil particles and is not highly soluble in water. It is not likely to contaminate surface or groundwater and is used in bating systems in very small quantities so is not likely to come in contact with residents. Termite control with the Sentricon System ® entails a 3-step process: (1) initial monitoring to pinpoint termite activity, (2) delivery of the bait, and (3) subsequent monitoring to provide ongoing protection of the structure.

The Sentricon baiting systems is the most extensively tested baiting system. (For other systems see University of Kentucky review of baiting systems.) It can be used as a preventive method for subterranean termites and a remedial control tool for existing infestations in structures. However, it could take from one month to more than a year to control an ongoing infestation and is in my opinion best used to prevent infestation. One of the biggest challenges in baiting is getting termites to find the baits in the first place. The timetable for discovery will vary from property to property, depending on such factors as termite foraging intensity, time of year, moisture, and food availability. On one infested property in Kentucky, more than a dozen monitoring devices were "hit" (attacked) by termites within two weeks of installation; on another home in the same neighborhood, no below-ground stations were attacked during a full year of intensive monitoring despite two concurrent termite swarms inside the home. Similar variances in bait detection by termites (and thus effectiveness of the baiting system to treat and eliminate an ongoing infestation) have been reported elsewhere in the country.

Thus, baiting can take more than a year to push back an infestation and baiting is expensive. While the initial cost of baiting is much less than the initial treatment with a chemical barrier. A typical "barrier" treatment may involve hundreds of gallons of pesticide injected into the ground alongside the foundation, beneath concrete slabs, and within foundation walls and may require the drilling of concrete floors, walkways and driveways. The total cost for this initial treatment can be up to $2,500 for a suburban home, but the maintenance contact is $100-$200.

Termite control with baiting entails a 3-step process: (1) initial monitoring to pinpoint termite activity, (2) delivery of the bait, and (3) subsequent monitoring to provide ongoing protection of the structure. Monitoring stations are installed around the perimeter of the house 10- to 20- feet apart. Stations are typically installed one to two feet from the foundation, to avoid soil that may have been treated earlier with a liquid termiticide. Patios, driveways, and other paved surfaces are not stations can be installed farther out from the foundation, in adjoining plant beds, etc. Additional stations are installed in suspected termite foraging areas, such as near pre-existing termite damage, stumps, woodpiles, or moist areas on the property.

Bimonthly thereafter the bait stations are inspected for termite presence. When termites are found in a monitoring station, the untreated wood is replaced with a perforated plastic tube containing bait laced with a slow-acting termite growth inhibitor (hexaflumuron) and the termites feeding on the wood pieces are carefully dislodged and placed within the bait tube. Eventually, these termites tunnel through and out of the perforated tube, carrying the bait back to the colony. After termites are no longer found in the bait tubes, the baits are once again replaced with untreated wood pieces and monitoring continues. Even if the termite colony threatening the structure has been eliminated, reinfestation can occur and homes protected with bait systems will need to be continually inspected, monitored and maintained to guard against reinvasion from new colonies or previously suppressed ones. Once the termite population has been eliminated, the pest control firm will continue to monitor at three- to four-month intervals for an indefinite period so that the annual contract cost is substantial and may be up to $350-$800 per year, though the initial cost would typically be in the same range.

Look for Termites

There are many species of termites. In the United States there are four groups of termites of concern: subterranean (including the Formosan termite), drywood, dampwood and powderpost. Subterranean termites and drywood termites are the two general types. Combined these termites cause $1.5 billion in damage annually in the United States. These termites perform the important task of breaking down the large quantities of dead and fallen trees and other sources of cellulose that continuously accumulate in the forests. Unfortunately they also attack wooden structures and other wood products like paper, books, insulation, and if left uncontrolled, will cause extensive damage to structures and paper materials. When termite damage becomes evident it is usually the result of years of infestation. In nature, termites are usually the secondary invader of woody plants already in decline. While buildings may become infested at any time, termites are often only discovered when a spring swarming is observed or a home is sold since a Wood Destroying Organism (WDO) inspection and a written report indicating any termite activity or damage is required to obtain a mortgage.

Subterranean termites are the most common termite in the United States. The Formosan subterranean termite is the most destructive of the subterranean termites because of the size of their colonies and the rate at which these huge colonies can consume wood. The Formosan subterranean termite is believed to have been imported to the United States from China via Japan and Hawaii. They have been reported in eleven southern states: Alabama, California, Florida, Georgia, Hawaii, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, and Texas. A single colony may contain several million individuals ten times the size of other subterranean species, they can forage up to 300 feet in soil and can consume as much as three quarters of a pound of wood a day and severely damage a structure in months rather than years. Once established, Formosan subterranean termites have never been successfully eradicated from an area, and pose a threat to nearby structures.

All subterranean termites are social insects that live in colonies in the ground below the surface. The colonies have three primary castes: workers, soldiers and reproductive. The workers are creamy white, are seldom seen, and feed on the wood causing all the damage. Workers are about a quarter of an inch long and can live for up to five years. The workers feed the other termites. The soldiers have yellow heads with large jaws and are about the same size as the workers. The soldiers literally defend the perimeter and mud tubs of the colony. Neither the solider nor the worker willingly expose themselves to light to prevent moisture loss and are rarely seen. The reproductive termites (Kings, Queens) are dark brown or black and up to a half an inch long. They have two pair of translucent wings that appear light colored of equal length that fall off shortly after swarming as part of the mating process. The mated pairs attempt to locate moist wood in contact with soil to start a new colony. Most pairs do not succeed. The shed wings or the observed swarming are usually the only indication of termite infestation. Swarming occurs in late winter to early summer in most parts of the United States. There are also secondary reproductive females in mature large colonies.

There are other signs of infestation that are often missed or ignored. Earthen (mud) tubes that extend over foundation walls, support piers, sill plates, floor joists, etc. are the most easily identifiable sign. The mud tubes are typically about the diameter of a pencil. Termites construct these tubes for protection from natural enemies and prevention of moisture loss as they travel between their underground colonies and the structure. To help determine if an infestation is active, the tubes may be broken open and checked for the presence of small, creamy-white worker termites. Some tubes are abandoned even as an infestation remains active and tubes are not always present if direct access to wood components is available from the soil. Stucco, brick veneer or insulation below grade provides the termites with hidden access into the structure. The infestation will typically go undiscovered until damage becomes obvious.

Another common indication of subterranean termite infestation is the presence of dark areas or blisters in wood flooring. However, subterranean termite damage can go unnoticed because the termites only eat the interior spring wood leaving the grain and exterior surface intact. However, the termite galleries can be detected by tapping the wood every few inches with the handle of a screwdriver. The damaged wood sounds hollow and the screwdriver may even break through the wood into the galleries. In traditional construction with a basement most termite infestations occur in the basement and the structural timbers immediately above the basement walls such as mudsills, studs, joists, subflooring and floors. Wooden posts, steps, door frames, and any wood embedded in concrete or dirt floors are very susceptible to termite infestation. When a home is built on a concrete slab the flooring and framework for the walls can be damaged by termites. Termites favor the areas around furnaces, chimneys, hot water heaters and hat water pipes that provide warmth and moisture during cold months.

Most homes in United States were treated to prevent termites during the initial construction process. Termite treatments either barrier chemicals or poisons were sprayed into the soil under and around building before concrete was poured during construction. Most new construction in the United States is required to have pre-treatments for termites. Typically, large volumes of termiticide emulsion were sprayed into the excavation to fill the soil around the foundation walls before the concrete is poured. Competently treated structures are expected to resist termites for 5-10 years. The treatments are not permanent so it is necessary to develop a strategy to prevent termite infestation early. It is easier and less toxic to prevent infestation than to treat an infested home. However, it is not advised to use the barrier chemicals which involve pouring hundreds of gallons of toxic chemicals into the ground every 5 years. In addition, regulations prevent the application of most if not all termiticide within 50 feet of water well. There are steps a homeowner should take to make a house less ideal for termite invasions to minimize the use of chemicals. The US EPA has developed their Pesticide Environmental Stewardship Program (PESP) to encourage the least toxic methods of controlling pests. The integrated pest management approach for termite control involves the following steps: Inspection, detection and monitoring.

The thorough inspections and periodic regular monitoring will help determine the location of any termite damage and its extent, as well as identify signs of previous and current infestation. Research from the Entomology Department of University of Florida found that properly trained termite dog and their trained handler are the most effective termite inspectors. This is not a joke, but it is really funny to have your house inspected by a beagle. Termite Dogs can smell termites, through drywall, concrete, paneling and all other building materials and sit down to indicate a find. The paper “Ability of Canine Termite Detectors to Locate Live Termites and Discriminate Them from Non-Termite Material” was published in 2003 by the University of Florida. They tested dogs specifically trained to detect. In field trials the dogs were able to accurately locate termites in 95.93% of the time which was better than the trained human inspectors.

Determine treatment plan. There is a difference between finding termites and finding "conditions conducive to termite infestations". Both situations need to be addressed, but usually in different ways. Eliminating conditions favorable to wood-destroying pests, mostly moisture-related problems, usually means repairs or alterations to the crawlspace, elimination of water pooling locations and leaks in basements, crawlspaces or other parts of the house or the area around it. Wood that is at least 30% water saturated provides enough moisture. Termites will find free-standing water such as condensation, rain or plumbing leaks and use this moisture as their main source for survival. The treatment options are bating with spot treatment and traditional chemical barriers. Termite baits use small amounts of slow acting insecticide to knock out populations of termites foraging in and around the structure. Some bait systems may even eradicate entire termite colonies. A chemical barrier is the other option plan and involves using hundreds of gallons of termiticide to create an unbroken barrier of treated soil around and under the foundation. The chemicals are injected under pressure and may usually require the drilling of concrete slabs, porches and patios. Termite treatment is not a DIY project. Many of the consumer available products do not work and application technique is essential to success.

Finally, monitoring is an important element of termite control which is often difficult to achieve. Termite treatment is not a one-time event, but an ongoing struggle. When using barrier chemicals, termites may find their way through tiny, untreated gaps in the soil since it is practically impossible to establish a continuous, impenetrable chemical barrier. In the case of baits, it may take months for termites to find the bait installations and several months to achieve control of the colony. For this reason it is advised by various extension offices and the EPA to maintain a monitoring and service agreement.

Inspector Marlowe

In the United States there are four groups of termites of concern: subterranean (including the Formosan termite), drywood, dampwood and powderpost. Subterranean termites and drywood termites are the two general types. Subterranean termites "nest" in the soil and from there they can attack structures by building shelter tubes from the soil to the wood in structures. Combined termites cause $1.5 billion in damage annually in the United States.

The most popular professionally applied conventional chemical treatments on the market are Premise (imidacloprid), Termidor (finpronil), and Phantom (chlorfenzpyr) range from slightly toxic to very toxic and vary in their solubility and affinity for soil. They are less environmentally persistent and more rapidly biodegradable, than previous generations of chemicals they work by acting as insect endocrine disruptors. They breakdown faster and do not last as long, but are still of concern and the EPA is taking a renewed look at endocrine disruptors that may impact other species and imidacloprid the active ingredient in Premise is on the final list. Ridding an infested house of termites or preventing termite infestation using the lest toxic method requires an integrated pest management approach that includes a series of methods for preventing or managing pest populations based on an ecological understanding of the problem. The US EPA has developed their Pesticide Environmental Stewardship Program (PESP) to encourage these methods.

The treatment options are bating with spot treatment and traditional chemical barriers. Termite baits use small amounts of insecticide to knock out populations of termites foraging in and around the structure. Some baits may even eradicate entire termite colonies. Termite baits consist of paper, cardboard, or other termite food, combined with a slow-acting substance lethal to termites. When needed, my baits will be laced with Termidor. Regardless of which bait is used, the process is lengthy and four or five times as expensive as chemical treatment, but uses less than 1% of the chemicals used in traditional treatment. Baits offer termites an easily accessed location to feed on wooden stakes, cardboard, or some other cellulose-based material. The toxicant-laced bait can either be installed initially, or substituted after termites have been detected in an untreated monitoring device. The more baits installed, the better the chances of locating termites. Planning, patience, and persistence are requisites for successfully using termite baits. This is a long term commitment and a slow solution if you already have termites

My property has a creek that is part of the Chesapeake Bay Watershed. My drinking water comes from the groundwater beneath my land. I am the steward of this portion of the water shed and as such I will not pump a hundred gallons or more of chemicals into the soil every few years. So I have embarked on a preventative program of baiting which requires monitoring of the baits every 60 days to see if they have attracted any termites. Before baiting I needed to determine if the property had been impacted by termites. The baits would be placed without chemicals if the structure was free of termites. Thus, I meet Inspector Marlowe and his owner Stephen Dodge of ProTech Termite and Pest Control. For several years running Inspector Marlowe was the prize winning termite detection dog. His is a beagle of advanced age and getting ready to retire and be replaced by a younger associate. He was a sweet dog and still very active and enthusiastic. When Steve put on the fanny pack with the dog kibble in it, Marlowe was ready to hunt.

The fist thing Marlowe did was to roll around in the grass to hide his sent. This is an instinctive move with beagles who I think tend to smell like Frito chips. Then it was onto the house and the hunt for termites. The whole experience was like watching someone walk their dog though your house. Marlowe covered the entire footprint of the house, every corner, wall and box in the basement. It was simple, quick and a bit funny. No intrusions were found on the lower level so there was no need to search the upper floors. How certain am I that Marlowe was effective?

Normally when you have a termite inspection, a pest management professional conducting a visual inspection relies on finding live termites, mud tubes, and/or damaged wood to confirm a suspected infestation. Dogs rely on smell, not vision, to detect a wide array of materials, including explosives, narcotics, missing people. Dogs can be trained to a high level of accuracy. A study was performed by Shawn E. Brooks, Faith M. Oi and Philip G. Koehler at the University of Florida. Florida has a huge termite problem and is a leader in the study of termite treatment options. Their paper “Ability of Canine Termite Detectors to Locate Live Termites and Discriminate Them from Non-Termite Material” was published in 2003. They tested dogs specifically trained to detect termites in the methods used by law enforcement to train explosive detecting dogs. In field trials the dogs reliably located termites in 96.67% of the containers (positive indications). The dogs responded to 1.73% of the empty containers (false indications). In all dogs trained daily for 3 weeks to 3 months were able to accurately locate termites in 95.93% of the time. This is much higher than the human ability to detect termites. As recommended by the study Marlowe has gone to termite refresher camp.

It is essential to continue monitoring for termites in the baits and add Termidor as needed. The success of the treatment method needs to be assessed occasionally, monitoring will detect any infestations as early as possible. So I look forward to meeting Marlowe’s successor in the future.

Termites and Integrated Pest Management

In the United States there are four groups of termites of concern: subterranean (including the Formosan termite), drywood, dampwood and powderpost. Subterranean termites and drywood termites are the two general types. Subterranean termites "nest" in the soil and from there they can attack structures by building shelter tubes from the soil to the wood in structures. Subterranean termites cause more of the damage to homes and structures than drywood termites so will be my primary focus here. Termites will attack any material with cellulose, including wood, paper coated wall board, and paper (as in that treasured book collection that occupies the lower level of my home). Wood that is at least 30 percent water saturated provides enough moisture. Additionally, termites will find free-standing water such as condensation, rain or plumbing leaks and use this moisture as their main source for survival. Termites have been a part of the ecosystem for thousands of years and aid in the decomposition of wood, freeing the nutrients in the decaying material for reuse by other organisms. Termites rely on eating the cellulose found in wooden structures, furniture, stored food and paper. It is virtually impossible to reside anywhere in the United States without confronting termite damage at one point or another.

No technique, from the traditional, blast it with chemicals to the alternative strategies are 100% effective all the time. The most popular professionally applied conventional chemical treatments on the market are Premise (imidacloprid), Termidor (finpronil), and Phantom (chlorfenzpyr) range from slightly toxic to very toxic and vary in their solubility and affinity for soil. They are less environmentally persistent and more rapidly biodegradable, than previous generations of chemicals. This all means that they breakdown faster and do not last as long. In addition, Premise and Termidor kill termites more slowly than the "older" chemicals after the insects come in contact with the treated soil. Studies indicate that "contaminated" termites may pass some of these non-repellent chemicals to other members of their colony which increases the overall impact of the termiticide. There are steps a homeowner should take to make a house less ideal for termite invasions to minimize the use of chemicals. Ridding an infested house of termites or preventing termite infestation using the lest toxic method requires an integrated pest management approach that includes a series of methods fro preventing or managing pest populations based on an ecological understanding of the problem. The US EPA has developed their Pesticide Environmental Stewardship Program (PESP) to encourage these methods. The integrated pest management approach for termite control involves the following steps:

Inspection, detection and monitoring. The thorough inspections and periodic regular monitoring will help determine the location of any termite damage and its extent, signs of previous and current infestation. Research from the Entomology Department of University of Florida found that properly trained termite dog teams are the most effective termite inspectors. This is not a joke, but it is really funny to have your house inspected by a beagle. Termite Dogs can smell termites, through drywall, concrete, paneling and all other building materials.
Identification. The next step is to correctly identify the species found on-site. Ant and termites are often confused.

Determine treatment plan. There is a difference between finding termites and finding "conditions conducive to termite infestations". Both situations need to be addressed, but usually in different ways. Eliminating conditions favorable to wood-destroying pests, mostly moisture-related problems, usually means repairs or alterations to the crawlspace, elimination of water pooling locations and leaks in basements, crawlspaces or other parts of the house or the area around it. If inspection did not find any current infestation a monitoring program combined with these physical changes to the structure to discourage infestation in the long run. If signs of infestation were found, it is possible to spot treat infestation areas using the least toxic chemical. (This is probably borates for wood protection, and replacement of damaged wood. Any replacement wood elements should be with borates, and the infested wood elements removed from site.)

Treatment. The treatment options are bating with spot treatment and traditional chemical barriers. Termite baits use small amounts of insecticide to knock out populations of termites foraging in and around the structure. Some baits may even eradicate entire termite colonies. Termite baits consist of paper, cardboard, or other termite food, combined with a slow-acting substance lethal to termites. Regardless of which bait is used, the process is lengthy and four or five times as expensive as chemical treatment. Baits offer termites an easily accessed location to feed on wooden stakes, cardboard, or some other cellulose-based material. The toxicant-laced bait can either be installed initially, or substituted after termites have been detected in an untreated monitoring device. The more baits installed, the better the chances of locating termites. Planning, patience, and persistence are requisites for successfully using termite baits. This is a long term commitment.
Monitoring. After treatment it is essential to continue monitoring for termites. The success of the treatment method needs to be assessed and once elimination of the infestation has been accomplished, monitoring will detect further infestations as early as possible.

With termites it is important to eliminate all infestation before too much structural damage occurs. Chemical treatment with termiticides is the least expensive and fastest method of treatment for termites. The chemicals in use today are far less toxic than previous generations. If you are strongly opposed to the use of pesticides around your home you should go with a baiting system. Although conventional liquid termiticides reportedly pose no “significant” hazard to humans, pets or the environment when applied according to label directions, they are still toxic chemicals. With baits, the total amount of pesticide applied is small in comparison to the gallons upon gallons needed to achieve a thorough and effective soil barrier treatment. In addition, drilling through driveways, garage, and slabs may be required to create a complete and unbroken chemical barrier surrounding a house. Regulations prevent the application of most if not all termiticides within 50 feet of water well. Termite baiting requires fewer disruptions within the home and is protective of ground water and drainage systems compared to conventional chemical treatment. Installation and subsequent monitoring of bait stations generally does not even require the technician to come indoors. Noise, drill dust, and similar disruptions associated with conventional treatment are avoided, but the baiting process can take months, possibly a full year to eliminate infestations. Traps were quietly and neatly installed yesterday and will be scanned and entered into the system for regular inspections tomorrow. The beagle is scheduled to inspect the home at that time. Updates in my adventures in IPM process will follow.

Keeping Moisture and Pests out of your House

Too much moisture in a home can lead to mold, mildew, and other biological growth. The presence of these molds can lead to a variety of health problems including allergies (my problem) asthma and more serious respiratory problems. In addition to health problems, excess moisture can lead to problems such as rot, structural damage, and paint failure and create a hospitable environment for pests. For example, termites require moisture in order to survive. Although ridding an infested house of termites requires an integrated pest management approach that includes a conventional chemical treatment or the use of baits, there are steps a homeowner should take to make a house less ideal for termite invasions to minimize the use of chemicals. Subterranean termites and drywood termites are the two general types. Subterranean termites "nest" in the soil and from there they can attack structures by building shelter tubes from the soil to the wood in structures. Subterranean termites cause more of the damage to homes and structures than drywood termites so will be my primary focus here. Termites will attack any material with cellulose, including wood, paper coated wall board, and paper (as in that treasured book collection). Wood that is at least 30 percent water saturated provides enough moisture. Additionally, termites will find free-standing water such as condensation, rain or plumbing leaks and use this moisture as their main source for survival.
Correcting and preventing moisture problems is a first defense against termites and should be considered before prophylactic application of barrier termiticide post construction. It is to be noted that many states (especially in the south east) require the application of termiticide chemical barrier before construction as part of site preparation. These preconstruction treatments are required to be effective for five years. It is reported that the newer, biodegradable chemicals are effective for 5-11 years; however, some termiticides breakdown easily in water and should not be applied within 50 feet of a water well or the water table. Other chemicals are more persistent and cling to soil. There are other techniques that should be used first and should be used as part of a termite management strategy. According to BIRC (The Bio-Integral Resource Center in Berkeley, CA) prevention and early detection are the most effective methods of reducing the use of toxic chemical in termite control. As a side note BIRC has an “ask the expert” section of their organization web site where they will help you identify the least toxic solution to your pest problem. They are really nice so ask away.
Rain water should not run up against the house (nor should plant irrigation water). The soil level against the exterior walls should slope away from the building. Even in areas where the natural topography is towards the house and artificial slope should be created in a shallow “V” to prevent water from pooling around the foundation. The ground around the home's foundation should be graded to slope down and away from the house at a rate of 1/2" to 1" per linear foot to drain surface water away from the house. If need be a French drain should be dug an adequate distance from the house. Most houses are built with the soil level sloped away from the building, but landscaping and time can undermine this. Plants should not be planted closely against a structure to avoid “watering the building” instead of the plants.
Water from down spouts should be directed away from the house, discharging at least a few feet from the foundation. If the natural flow of water is to pool in any location, it may be advisable to direct all down spouts to a dry well system or pipe to a more natural drainage location. Test any underground drains with a hose to make sure they are working properly. Often underground drains become blocked with debris or broken and allow water to drain against the building. Drains that are not working should be repaired or replaced. Be sure that driveways, sidewalks, and patios slope down and away from foundation walls at 1/4" per linear foot.
If these solutions do not eliminate a moisture problem then the next steps will have to be taken. In extreme cases, you may have to dig out around the foundation and replace the fill with an exterior drain tile and with a good draining material such clean gravel. Because this can be very expensive in existing homes, all the previous solutions should be rigorously tried first. In some areas, there may not be enough room outside the dwelling to provide proper drainage - in these cases; it is often recommended that interior drain tile and a sump pump be installed to remove water from basements and crawlspaces. This is very expensive and messy, but is extremely effective.