by Michael F. Potter, Extension Entomologist
University of Kentucky College of Agriculture
No structural pest causes more confusion than termites. Most homeowners have little knowledge of these troublesome insects, and what it takes to get rid of them. Our understanding of termites has progressed considerably in recent years.
New management tools have emerged, and a significant number of pest control firms are now using baits as an alternative form of treatment. This publication will help homeowners understand termite baits so that they can make a more informed purchasing decision.
TERMITES IN PERSPECTIVE
Subterranean termites, the variety common to Kentucky and most other states, live below ground in cooperative, intermingling groups known as colonies. Mature termite colonies tend to be decentralized entities occupying multiple nesting and feeding sites, interconnected by underground tunnels. The dimensions of a colony can be quite variable. Larger colonies can have hundreds of thousands to millions of individuals, occupying areas of up to half an acre. Smaller colonies may contain less than 10,000 individuals, with a foraging "footprint" no bigger than a bedroom. In some cases, larger but fewer colonies may be present; in others, individual colonies may be smaller and more numerous. In 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.
Subterranean termites excavate narrow, meandering tunnels through soil, eventually encountering wood, their primary food. Decaying tree roots, logs, stumps, woodpiles, and plant debris afford a ready and abundant supply of food for the colony. In nature, termites are very beneficial since they aid in the decomposition of organic matter and the return of nutrients to the soil. Occasionally during their persistent foraging, termites encounter wood within buildings. Once a suitable feeding site is found, the workers establish an invisible odor trail to attract other termites to the structure.
Subterranean termite infestations can go undetected for years, hidden behind walls, floor coverings, and other obstructions. Over time, significant damage can result. The cryptic nature and tenacious foraging habits of these insects also pose a challenge to control efforts. Unlike other services such as plumbing or electrical work, termite control involves living creatures. Traditional treatments may fail at times, underscoring the need for other forms of management.
CONVENTIONAL "BARRIER" TREATMENT
For years, the standard method of controlling subterranean termites was to apply a liquid pesticide, known as a termiticide, to the soil. The goal was to create a continuous chemical barrier around and under the building in order to block all potential routes of termite entry. Termites attempting to penetrate the treated soil were either killed or repelled. In actual practice, there are many obstacles to achieving such a barrier. Many potential termite entry points are hidden behind walls, floor coverings, and other obstructions. Even where access for treatment is possible, it is hard to uniformly wet soil and achieve thorough coverage. 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. Homeowners sometimes object to the drilling and disruption that such treatments often require.
ALTERNATIVE APPROACH: TERMITE BAITS
Termite baiting employs a very different approach. With baits, small amounts of material are deployed like edible "smart missiles" to knock out populations of termites foraging in and around the structure. Foraging termites consume the bait and share it with their nestmates, resulting in a gradual decline in termite numbers. Some baits may even eradicate entire termite colonies. A comprehensive baiting program then seeks to maintain a termite-free condition on the customer's property through ongoing inspection, monitoring and re-baiting as needed.
Slow-acting baits (such as the Sentricon Colony Elimination System pictured above)
can destroy large numbers of termites foraging in the vicinity of a structure.
(illustration courtesy of Dow AgroSciences)
The baits consist of paper, cardboard, or other palatable food, combined with a slow-acting substance lethal to termites. The bait must be "tasty" enough that termites will readily consume it, even in the presence of competing tree roots, stumps, woodpiles and structural wood. If the bait kills too quickly, sick or dead termites may accumulate in the vicinity of the bait stations, increasing the chance of avoidance by other termites in the area. Delayed-action also enhances transmission of the lethal agent to other termites, including those that never fed on the bait. Entire colonies can be eliminated in this manner, although total colony elimination is not always necessary to afford structural protection.
PATTERN OF USE
Various methods of termite baiting are employed by pest control firms. Some baits are inserted below ground out in the yard, while others are installed inside the building in the vicinity of active termite mud tubes. On some properties, baits may constitute the only form of treatment; on others, they may be supplemented with a partial or complete liquid application.
Installation Below Ground
Most termite bait components (paper, cardboard, etc.) decompose rapidly under ground. Consequently, most installations initially utilize untreated wood in the stations. Once termites are detected in the wooden monitors, the bait material is added. Termites cannot see or smell the baits underground; they more or less wander into them during their persistent foraging activities. To increase the odds of discovery, the stations are installed at fixed intervals (typically 10 to 20 feet apart) around the entire outside perimeter of the building and in known or suspected areas of termite activity (e.g., around woodpiles, stumps, moist areas, and adjacent to previous termite damage). With patience and a little luck, the termites eventually find and feed on one or more of the bait installations.
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. For example, 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 have been reported elsewhere in the country.
Because subterranean termites feed at multiple locations within their foraging area, chances are good that one or more bait stations will eventually be found and fed upon. In temperate climates such as in Kentucky, bait discovery usually will be greatest from spring through fall when termites are most active. Baiting during late-fall and winter is generally less fruitful. Termites may be found in below ground stations at sub-freezing temperatures, but their feeding activity and effects of the bait are greatly reduced. At times of the year when the ground is frozen, snow covered , or saturated, inspection of bait stations can often be curtailed until conditions once again become favorable for termite foraging and feeding.
The more bait stations installed, the better the chances of locating termites. Installing more stations increases the odds of encountering multiple colonies, or weakly associated "satellite nests" of the same colony -- any of which could be of potential risk to the structure. Planning, patience and persistence are requisites for successfully using below-ground termite baits. Regardless of which product is used, the homeowner must be prepared and willing to accept the possibility of a lengthy baiting process.
Baits can also be installed above ground, in known areas of termite activity. Typically, the stations are installed directly in the path of active termite tunnels after the mud tubes have been broken. Other times, they can be mounted directly over termite-infested wood, drywall, or other surfaces. Effects tend to be more rapid with above-ground baiting, since the procedure does not require waiting for termites to find the below-ground installations. They are normally used in conjunction with below ground baiting, rather than as a stand alone.
COMMERCIAL BAIT PRODUCTS
Discussed below are various professionally-installed termite bait systems, and another one marketed directly to homeowners.
This product/system has been the most extensively tested of those currently on the market. Consequently, it will be discussed in some detail. The Sentricon Termite Colony Elimination System was developed by Dow AgroSciences (Indianapolis, IN), and is sold only through authorized pest control firms. The bait contains a slow-acting ingredient which disrupts the normal growth process in termites (i.e., termites die while attempting to molt). 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.
- Step 1. Monitoring- Termites are detected by installing plastic monitoring stations around the perimeter of the building.
- The station housing (pictured above) is a hollow green plastic cylinder, about 10 inches long by 2 inches wide, with slits along the sides for termites to enter. Initially, each station is provisioned with two untreated pieces of wood, intended as monitoring devices for the presence of termites in the area.
The station is inserted into an augured hole in the ground, with the cover flush with the soil surface. Monitoring stations are installed around the outside perimeter of the building, at about 10- to 20- foot intervals alongside the foundation. Narrower intervals, while more effort to install and inspect, increase the odds that termites will encounter them during foraging. Stations are typically installed about 12 to 18 inches from the foundation, to avoid soil that may have been treated earlier with a liquid termiticide. Patios, driveways, and other paved surfaces are not a problem unless soil access is prevented around the majority of the structure. Oftentimes, stations can be installed farther out from the foundation, in adjoining planter boxes, etc. When necessary, stations can also be installed under pavement.
- As a supplement to installations along the foundation, additional stations are installed in suspected termite foraging areas, such as near pre-existing termite damage, stumps, woodpiles, or moist areas on the property. Periodically thereafter (monthly, bimonthly, etc.) the wood monitoring devices within each Sentricon station are inspected for termite presence.
- Step 2. Bait Delivery- 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 (noviflumuron).
- To hasten the overall process, termites feeding on the wood pieces are carefully dislodged and placed within the Baitube. Eventually, these termites tunnel through and out of the perforated tube, reuniting with their nestmates in the soil. In doing so, they leave behind a colony-specifict scent that promotes recruitment of other nestmates to the bait. In order to promote additional "hits" (attacks) on stations, additional stations containing wood are installed near those receiving Baitubes.
- Inspection of all Sentricon stations, with and without substituted bait tubes, continues until no more live termites are discovered. Empty, moldy or degraded baits are replaced and additional stations added as deemed necessary.
- Step 3. Continued Monitoring-
After termites are no longer found in installed Baitubes, the baits are once again replaced with untreated wood pieces and monitoring continues. Even if the termite colony threatening the structure has been eliminated, termites from neighboring colonies can reinvade the area. Reinfestation can also occur if only part of the original colony or colonies was eliminated. Consequently, structures protected with Sentricon (and all other bait products and 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.
Termites feeding on wood monitoring pieces
Independent research studies, including some performed in Kentucky, indicate that the Sentricon® Colony Elimination System is an effective termite control option. Some of these studies involved structural that could not be controlled using conventional liquid methods. Despite Sentricon's demonstrated effectiveness, diligence and persistence are requisites for success — as is true for any termite management program. In order to use Sentricon, companies must receive training and adhere to rigid quality assurance standards required by the manufacturer. Various enhancements have been added in recent years to facilitate performance and serviceability. Aboveground stations are available to hasten delivery of bait to termites evident within in the structure. Another enhancement, "ESP Technology," utilizes a wand-like electronic device to detect termites within stations without opening or disturbing them.
FirstLine® is another bait product option, manufactured by FMC Corporation (Philadelphia, PA ). Installation and servicing procedures are fairly similar to those for Sentricon. FirstLine bait stations have a somewhat different appearance, and the corrugated cardboard food source contains sulfluramid, a compound that interferes with the termites' ability to derive energy from food.
Most pest control companies using FirstLine also perform a partial or full liquid treatment. (Sentricon is often used as a "stand alone" installation). Research studies evaluating the effectiveness of FirstLine have been more limited, and there is uncertainty as to whether the bait or the supplemental liquid application is having the greater impact on the termite infestation.
EXTERRA™ Another product used by some companies is the Exterra™ Termite Interception and Baiting System (Ensystex, Inc., Fayetteville, NC). The bait used in Exterra contains diflubenzuron, a termite growth regulating agent in the same chemical group as Sentricon's active ingredient, noviflumuron. Both compounds are chitin synthesis inhibitors and kill by disrupting the termite molting process. Installation procedures are similar to Sentricon and FirstLine, but subsequent servicing of stations may be a bit less frequent (45- to 90-day inspection intervals rather than initial visits that are monthly). As with Sentricon, Exterra is marketed as a stand-alone baiting system with no supplemental liquid treatment required. Fewer independent research trials have been conducted with Exterra, making it hard to say whether the products are comparable in overall performance.
SUBTERFUGE® Subterfuge is a relatively new termite bait manufactured by BASF Corporation (Research Triangle Park, NC). The active ingredient, hydramethylnon, affects termites in a manner similar to sulfluramid, the ingredient in FirstLine. Unlike other systems on the market, no wooden monitors are used prior to installing the baits, which are inserted from the outset. There have been few published studies evaluating the bait's effectiveness.
ADVANCE™ TERMITE BAIT SYSTEM This new bait system employs the same active ingredient (diflubenzuron) found in Exterra. Installation and servicing intervals are similar. Advance and Exterra both have station designs that reportedly allow termites to transition more readily into the bait after initially feeding on wood monitors. Independent evaluations of the bait's effectiveness are still rather limited.
This bait product, sold in retail stores, is marketed specifically for use by homeowners. The Terminate™ Termite Home Defense System consists of small, 4 by 1-inch hollow plastic stakes provisioned with sulfluramid-treated cardboard (the same ingredient in FirstLine).
The baits are installed at various locations around the outside of the home and inspected periodically by the property owner. The treatment cost for a box of Terminate bait stakes (under $100) is tempting, considering that a professional treatment using bait or liquid can cost well over $1000. There are issues pertaining to use of Terminate, however, and it is questionable whether it will protect a home from termite attack. As part of a 1999 settlement with the Federal Trade Commission and several state Attorneys General (including Kentucky), product directions now state that Terminate is not recommended as a sole protection against termites. Moreover, for active infestations the buyer is advised to get an inspection and treatment by a professional.
Successful termite baiting requires proper installation, monitoring and bait replenishment, plus ongoing surveillance of the structure. When using baits, supplemental treatment measures also may be necessary. For these and other reasons (see Entfact-642, Do-It-Yourself Termite Baits: Do They Work?), baiting is usually best left to professionals.
BAITS OR BARRIERS...WHICH IS BETTER?
This is the most common question from homeowners trying to decide which form of treatment to purchase. The question is a difficult one with no simple answer. Factors to consider in the purchasing decision include:
- Are you opposed to having your floors and walls drilled, or furnishings moved? Homeowners considering a bait treatment are usually relieved to learn that their carpeting won't have to be rolled back, their floors extensively drilled, or furnishings moved, as is often the case with conventional liquid applications. The technician may not even need to come indoors to install or monitor the stations. Drilling noise, concrete dust, application hoses, and similar disturbances are avoided.
- Are you opposed to having pesticides applied in and around your home? Conventional liquid treatments utilize hundreds of gallons of termiticide, injected into the soil under and around the house. Health and environmental risks from such treatments are generally considered negligible, but some householders still are apprehensive. With baits, the amount of pesticide applied is minute and confined in tamper-resistant stations.
- Are there construction features that make it hard to treat with a liquid? Some buildings have wells, cisterns, nearby ponds or streams, plenums, sub-slab heating ducts, drainage systems, inaccessible crawl spaces, or other features that complicate treatment of soil with a liquid. With baits, such conditions aren't a problem and may be the only feasible form of treatment. Houses that were unsuccessfully treated with liquids also are candidates for baits, since they do not require gaining access to hidden or hard-to-reach areas.
- How quickly must the infestation be eliminated? A limitation of all termite baits is that they are relatively slow acting compared to the effects of liquids. Several months may pass before termites find the baits underground and distribute them to their nestmates. Consequently, the elimination process can take several months or longer to complete, and a degree of feeding and damage may occur before the bait takes effect. Homeowners with a severe termite infestation or those involved in a real estate transaction may not want to wait this long — preferring instead that a liquid be applied alone or in combination with baits.
- How much are you willing to spend for treatment? Termite services vary in price from about $700 to $2500 for initial treatment, and $70 to $350 for the annual renewal warranty in case termites return. Baiting often is more costly than liquid treatment because the process requires several visits to the structure to monitor for termites, and add or replenish baits. Homeowners should consider both the initial treatment price and the annual renewal fee in making their purchasing decision. Whereas liquid treatments usually entail an annual followup inspection, bait renewals typically require three or four visits per year, for as long as the contract is in effect. Thus, the annual renewal fee for baiting may be two to three times higher than for liquid treatments. Failure to maintain the annual renewal agreement can be a prescription for disaster with baits, since there is no residual pesticide left in the soil after the termites have been eliminated. Ongoing structural protection depends on monitoring for the possible return of termites in the future.
In summary, termite baits are useful and effective tools for managing infestations. Regardless of which product/system is used, they will not work by simply hammering a few stations into the ground and walking away. Success will require thoughtful installation and diligent monitoring by an experienced technician, backed by a responsible pest control firm.
Where trade names are used, no endorsement is intended, nor criticism implied of similar products not named.
For further information about the products mentioned in this publication, contact the manufacturer , your local termite control professional, state regulatory agency responsible for pesticide usage, or the university cooperative extension office in your area.
CAUTION! Pesticide recommendations in this publication are registered for use in Kentucky, USA ONLY! The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication.
Of course, ALWAYS READ AND FOLLOW LABEL DIRECTIONS FOR SAFE USE OF ANY PESTICIDE!