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Wood-Destroying Insects

Except for the most northern states, wood-destroying insects are a concern to homeowners. Why? Because they are "wood destroying" and most of our homes are built with wood. They will eat your house!

Various state regulations have created different names for these insects to handle the inevitable challenges and semantic arguments. In some cases, they are called wood-destroying insects, in others they are wood-destroying organisms (WDO) and in still others they are simply called what they are: termites, carpenter ants, carpenter bees, powder post beetles, etc.

In this issue, we will examine a few interesting facts about the most common and most destructive type of wood-destroying insects, termites.

Unlike most other WDO, termites eat the wood. Others nest in the wood and are therefore less destructive. Termites are organized and hungry! Colonies will often have tens of thousands of members. That’s a lot of mouths to feed. While often confused with ants (of the same insect family as bees and wasps), termites are of their own insect order (Isoptera). The origin of the name is Greek, "Iso" meaning equal and "pteron" meaning wing. Winged termites have four wings (two on each side) of equal length. Winged ants, in contrast, may have four wings, but the rear wings are smaller than the front. Ants also have a waist (an "hourglass figure"), while termites have a thick (or almost no) waist.

Termites are industrious. Each member has a clear function within the colony. There are workers, soldiers and reproductives. The workers are small (about 1/8 inch long) and they are blind and wingless. They forage for food and water, construct and maintain the mud tubes, feed and groom other termites, care for eggs and the young, and participate in some colony defenses. The soldiers are larger than the workers and handle most of the colony defenses. The reproductives’ purpose is obvious.

There are many types of termites - more than 2,500 worldwide. The most common in the United States are subterranean, drywood and dampwood. Due to some careless control of materials imported into the United States, Formosan termites have also been discovered in this country but are still far less common than the others. Formosan termites are of increased concern because they are larger and more aggressive.

Although termites are the king of WDOs (they eat wood), they are slow eaters. Thus, discovering a termite infestation is not cause for an emergency. Treatment is effective and can be handled in a few months without causing additional problems.

Subterranean termites are the most common. They mostly nest in damp ground (for the moisture) and travel to your house for food. You might say they commute to work! Except in limited stages of the life of certain members of the colony (mostly the reproductives), they never go out in the light. In fact, the workers of most species do not have eyes.

Mud tubes, typically ¼ to 1 inch wide, extending from the ground to the wood framing of your home, are the most common evidence of subterranean termites. Mud tubes are typically on the foundation walls but can be freestanding. Termites are pretty good builders! Mud tubes allow the termites to commute to your home (their restaurant!) without being in daylight. Other evidence that you have a termite problem is damaged wood. It may appear rotted, but close examination will reveal a cellular-like structure, as the termites eat the softer cellulose between the harder grain structures. Some woods are favored over others, mostly because they’re softer (there is no evidence that termites choose wood based on flavor or other gourmet characteristics!).

So, you have termites. Now what? There are many approaches to control, some of which favor new construction. In fact, in most states where termites are a common problem, there are building code requirements specifically related to termite control. Such standards vary by state. State agencies can provide those standards. In most states, the Department of Agriculture and/or Department of Consumer Services provide such standards. Some states, such as Florida, have a Bureau of Entomology (insects are a big issue in Florida).

In an existing home, soil treatment is generally the best. Treatment falls into two categories, repellent and non-repellent. Repellents cause termites to avoid the area. Thus, the treatment must be continuous to be effective. Spot, or localized, treatments do not work since termites will find their way around them. Repellents should be applied by licensed, trained applicators/companies. Non-repellents are toxic to termites and will typically eliminate a colony near your house within three to six months. However, non-repellents are still less common in the marketplace.

In the past, chlorinated hydrocarbons, such as Chlordane, were commonly used as a repellent for termite protection. However, such materials have been banned in most states due to health and environmental concerns. Other materials have been developed to replace chlorinated hydrocarbons and are generally effective. These include the brand names of Dragnet and Demon. Chemically, they are pyrethroids. These repellents require proper application to be effective.

Any termite treatment should be renewed periodically. Regular inspections (annual in most states) are important. A credible termite control company should provide a warranty for the effectiveness of their work. In new construction, the essential approach to termite control includes physical barriers and separation between the ground and the wood. There are many variations on this approach, most driven by individual state regulations.

If you have a termite problem, you should do the following:

  • Talk to the appropriate agency in your state to find out what is permitted for termite control and what licensure is required for termite control companies.
  • Talk to at least three different termite control companies to get information about cost, frequency of inspections and warranties.
  • Compare what you learn and select a company.
  • When their work is complete, be sure to get and keep all the related paperwork.

Do not try to treat termites yourself, as the chemicals are dangerous and you probably will not be effective.

Finally, while we usually think of termites as bad, in nature, like most things, they do make positive contributions in the world’s ecosystems. Perhaps most significant is the role they play in recycling wood and plant material. Also, their tunneling helps ensure that soils are porous, supplied with nutrients and healthy enough to support plant growth.

Our goal is to keep them from eating our houses and to do so in an environmentally friendly way.


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