Thursday, October 20, 2011
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.