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All About Termites Log homes, like other structures made from wood, are subject to attack by a variety of wood destroying insects including termites. Although there are thousands of known termite species, there are only a few that are of concern to the log home owner. These can be broken into two main varieties, drywood termites and subterranean termites.
Drywood Termites
Drywood termites are found along the coastal areas of the United States including Florida, Mississippi, Louisiana, Texas, and California. Although named drywood termites, these termites can’t live in completely dry wood since they rely on the moisture in the wood for their source of water.
Drywood termites live in small colonies consisting of a few hundred individuals. Like all termites, the colonies are divided up into different castes. At the center of the colony is the queen who is responsible for producing the eggs that ensure the continuous viability of the colony.
A king termite is often found accompanying the queen although his presence is not necessary for colony success. Other caste members include soldiers who guard and protect the nest, reproductives who can establish new colonies, and workers who eat the wood and feed the rest of the colony.
Most drywood termite colonies become established through exposed wood ends accessible from cracks and crevices. Signs of an infestation include finding small hard fecal pellets on the floor or other surfaces and seeing winged termites, especially on windowsills.
Since drywood termite colonies are relatively small, it usually takes several years for an infestation to cause structural damage. However, if left untreated, damage from a drywood termite infestation will eventually result in costly repairs.
Subterranean Termites
In most areas of the country the term termites refers to subterranean termites. As their name implies, subterranean termites spend most of their time in the soil, typically two to four feet below the surface. Workers, soldiers, reproductives, along with the king and queen make up a subterranean termite colony that typically consists of several hundred thousand termites.
When foraging, workers spread out from the nest, usually just beneath the surface of the ground, looking for food. They feed on cellulose including plant materials, dead tree roots and limbs, and the wood in a home. Since there are many thousands of feeding termites in a colony, subterranean termites can do a substantial amount of damage in a fairly short period of time.
In addition to cellulose, termites are attracted to water. If these two elements can be combined as in wet wood, an ideal environment is created for termite attack. Moisture control and the avoidance of wood to ground contact are the most important factors in removing conditions attractive to termites. Much can be done during the design and construction stages of a log home to eliminate conditions conducive to termite attack.
The first indication of a termite infestation is usually the presence of mud tubes going up walls, piers, or other vertical surfaces. Termites make these tubes in order to maintain a moist environment. Since they have soft bodies they rapidly lose water when exposed to dry air and the mud tubes give them protection from both predators and dehydration.
Another sign of a termite infestation is a termite swarm within the home. Many people mistakenly identify swarming termites as flying ants but it’s easy to tell the difference if you know what to look for. Ants have a narrow waist whereas the termite’s body is fairly straight back to the abdomen.
When termites swarm in the thousands, a homeowner’s first impulse is to run for the can of pesticide and spray them down. There is no reason to do this since all of the swarming termites will be dead in an hour or so anyway. The best way to handle them is to vacuum them up. The next thing to do is to call a pest control professional for a termite inspection. The presence of swarming termites in a home is a sure indication that a mature termite colony is located within or close to the structure.
Formosan Termites
Over the past few years, an imported termite species, the Formosan termite, has invaded a number of southern and southwestern states. Formosan termites are a variety of subterranean termites whose colonies may contain over a million individuals.
Although similar in appearance to native subterranean termites, their voracious appetite and large colony size set them apart from our native species. They have been known to cause significant structural damage in a matter of months. They also tend to establish aerial infestations with nests called cartons that have no contact with the ground. This is one reason they are so difficult to control. However, Formosan termites need the same set of conditions to survive as our native termites.
Termite Treatments
Soil treatments
In the past, soil poisoning was about the only method used for protecting a structure from termite attack. Due to their negative impact on the environment, many of the chemicals used 15 years ago are no longer available.
The new soil termiticides fall into two basic categories, repellent and non-repellent. The objective of a repellent soil termiticide is to form a barrier around the structure that termites will not penetrate. This is the type of treatment typically used in "pre-treatment" site applications prior to construction.
For remedial treatments the termiticide is injected into the soil to the base of the foundation and poured into a trench around the foundation perimeter. One limitation of this type of treatment is that if the soil surrounding the structure is disturbed, it may provide a path for termites to enter within the treated barrier.
The newest technology in soil treatments is development of non-repellent termiticides. Foraging termites do not detect these products and they freely pass through the treated soil. The foraging termites carry minute amounts of the toxicant back to the nest and eventually the termite colony is eliminated.
Since non-repellent termiticides have only been on the market a few years the longevity of their efficacy is not yet known. So far the results over a five year period look quite promising and many professional applicators have incorporated non-repellent termiticides into their termite control programs.
Termite baits
There are a number of termite baits now available to pest management professionals. Although the mode of action and installation instructions may differ, the basic concept for all termite baits is the same. The objective is to get foraging termites to feed on the bait and take it back to the nest eventually killing all of the termites in the colony.
Bait stations containing cellulosic materials are placed around a structure with the hope that termites will find one or more of them and begin feeding. Some of the baits require an initial non-toxic attractant be replaced with a toxic bait whereas others start off with a bait containing an active ingredient.
One problem with baits is the time it takes for termites to find and begin feeding on a bait. It may take a few weeks or many months before control is achieved. In the meantime, termites may continue their feeding activity on the structure.
Wood Treatments
Pressure treating wood with various chemicals has been used for years as a method to prevent termite attack. As in the case with soil termiticides, many of the chemicals that were used in the past are no longer available. Wood pressure treated with CCA (Chromated Copper Arsenate) is commonly used in most of the country. However, a recent agreement between wood treating companies and the EPA will result in a removal of arsenic from many of the formulations used to protect wood from termite attack.
As of January 2004, the EPA will not allow wood products intended for residential use to be treated with CCA. One alternative for CCA already in use is a borate, disodium octaborate tetrahydrate. A few log home manufacturers have been pressure treating their logs with borates for several years and report excellent resistance to termites and other wood destroying insects.
In addition to pressure treatment, logs and dimensional lumber may be impregnated with borates through the dip-diffusion process. In this method of treatment green wood is immersed in a vat of concentrated borate solution. When removed from the treating solution, the wood must be protected from rain or snow while the borate diffuses into the wood. Once the diffusion process is complete, the wood may be dried or handled the same as untreated wood.
The advantages of borate treatments include:
- No change in the wood’s appearance or shaping characteristics.
- Low mammalian toxicity.
- Not considered a hazardous waste.
- Imparts protection from termites, wood boring beetles, and decay fungi.
- Long lasting if protected from the elements.
The main disadvantage is that borate treated wood is not suitable for use in contact with the ground or continuous immersion in water.
Topical treatments
Topical applications of various chemicals have been used for years to make wood resistant to termite attack. Some chemicals like pentachlorophenol and creosote are no longer available for general use.
Within the past ten years pest management professionals and homeowners have found topically applied borate formulations to be an effective method of termite prevention and control. Two basic borate formulations are being used in these applications, pure disodium octaborate tetrahydrate (DOT), and a combination of borate and liquid glycols.
Log homes, like any other structure containing wood components, are subject to attack by termites. Many aspects of a log home’s design and construction can help reduce those conditions that make a home attractive to termites.
All too often a log home owner worries about protecting their logs but forgets about the other wood components of the home such as floor joists, sill plates, and pier assemblies. Soil termiticides, termite baits, and wood treatments all have a role in an effective integrated termite avoidance program, but they are not substitutes for quality design, construction, and maintenance.
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