WoodInfesting Insects: Termites

by Steve Sproul

CA General Contractor#450095

Termites-Termites are the most destructive of the insects that will be discussed here. They are serious structural pests because they feed on the cellulose found in wood. There are over 50 species of termites in the U.S., but the species known collectively as subterranean termites accounts for more than 95% of all termite damage. Subterranean termites nest only in the ground but will readily travel 30 or 40 yards from the nest to above-ground feeding sites.

All termites are social insects that live in colonies. Subterranean termites have two distinctive forms: winged and unwinged. Called swarmers or reproductives, winged kings and queens, are up to 1/2 in. long , dark colored and can easily be confused with winged carpenter ants. But ants have a constricted waist, elbowed antennae and wings of unequal length. Winged termites, on the other hand, have thick waistlines, wings of equal length and straight or curved antennae. Close up, the antennae look line a string of beads. The other form, worker termites, are 1/4 in. long, wingless, eyeless, soft-bodied, white insects that are sterile. Workers avoid light, so are rarely seen in the open.
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When a termite colony matures (that takes from 2 to 6 years), large numbers of winged individuals will emerge during the daylight, often after a rain. The most common sign of an infestation is a swarm of winged termites congregating on a windowsill or other light sources. After the swarm disperses, the king and queen will find a nest site under a rock or in the soil and begin raising young (nymphs). The nymphs mature into large jawed soldier termites, which defend the nest, or into workers, which feed and care for the queen and young, build the nest and forage for food. Colonies can include hundreds of thousands of termites. Reproductively mature males and females can develop from wingless nymphs.

The three critical needs of a termite colony are high humidity (moisture), a constant food source of wood or cellulose, and protection from long periods of freezing weather. Although carpenter ants can hibernate, termites must continue to feed and be active throughout the winter. Because they are cold-blooded creatures, severe cold prevents termites from feeding above ground in unheated situations.

Nesting in the soil keeps the colonies well-insulated and provides the needed humidity. Buried wood, tree stumps and fence posts all provide termites with below ground food sources, but termites will feed above ground when conditions are right. Termites are highly attracted to odors given off by decaying or wet wood.

When feeding on wood above ground, termites will often construct mud-like shelter tubes to protect themselves from temperature extremes, dessication and enemies. These tubes are made of soil, wood and salivary secretions, and can be repaired quickly if damaged. Termites do not always need to construct tubes: cracks in cement slabs, any direct wood-to-soil contact, or hollow concrete blocks allow termites direct and hidden access to structural wood without leaving any visible tubes. the placement of stair carriages, wooden posts or partition walls in a basement before concrete is poured invites problems and makes the infestations hard to detect.

Termites leave little active sign on t he outside of the wood they infest. Tapping infested lumber with the handle of a screwdriver or hammer will produce a dull hollow sound. Water stains or other signs of moisture problems may appear on the surface. If you probe the infested wood with a sharp screwdriver, you will find many small chambers (galleries) that may or may not be crawling with small white insects. Damage is usually greatest in softer spring wood, and the gallery walls will be coated or spotted with a mixture of digested wood and soil that looks like dried oatmeal.

When looking for termites outdoors, examine the foundation for shelter tubes coming from the soil. Look closely at areas such as attached porches, sidewalks and connecting patios that provide confined or hard-to-see spaces where termites can work up into the home. Check windows and door frames, too. Indoors probe or carefully tap door and window trim, baseboards and wood flooring. Do not overlook cracks and expansion joints in the foundation, and pay extra attention to places where utility pipes enter the foundation. If the house is built on a crawl space, you need to go into the crawl space and look for tubes on chimney bases, piers and along the beams and joists. Any standing water or leakage problems should be noted and corrected.

Preventing damage-Termite problems can be prevented through sound design and some common sense. In simple terms this means denying termites access to food, moisture and shelter. All wood to soil contacts should be eliminated including details such as trellises, stair carriages and fence posts. The grade level should be at least 6 in. below the top of the foundation or the siding, which fill force the termites to leave visible shelter tubes over the foundation and will make detecting them easier. In crawl spaces, there should be 18 in. of clearance between floor joists and soil and minimum of 12 in. between the beams and soil. These minimums can only be truly appreciated once you have experienced a tight squeeze of less while unde r a house.

Remove all wood, and cellulose debris, ie; piles of sawdust, branches, cardboard, leaves and scraps of wood, from under and around the house. Do not bury scrap wood or paper on the property during of after construction. Remove all stumps from underneath and around the foundation. Using scraps as fill under porch steps is a common and costly mistake. Fill cracks and voids or expansion joints an openings in the foundation with either cement grout or roofing-grade coal-tar pitch. Termites will exploit any cracks they find.

Sump pumps to drain water from under the house and around foundations, french drains, polyethylene vapor barriers and particularly foundation vents will prevent moisture buildup and lessen the potential for attracting termites. Any wood in contact with the soil (including concrete) should be pressure-treated lumber, which is impervious to termites.

Controlling Termites-Because termites nest in the ground it is virtually impossible to find their nest and treat it directly. Placing a protective envelope of poisoned soil around the foundation of a house creates a barrier that will stop termites. Chemical treatment of the soil before construction is far less expensive, allows for more accurate and efficient application of the chemicals and is less disruptive than the procedures used in treating existing structures. When building a home in a termite-prone area, insist on a chemical pretreatment before foundations or slabs are poured.

Once a home is built, the problem is how to get the pesticide between the soil and the homes foundation without leaving any gaps. These chemical treatments require specialized drills, pressure injectors and pressure pumps with high volume tanks. Application rates run from two to four gallons of mixed spray per ten lineal feet of foundation and drill holes through concrete slabs are spaced as close as one foot. Proper treatment is a real art and improper treatment can contaminate the home or well water. When dealing with termite proble ms in existing homes the best advice is to call in the services of a licensed pest control operator.

There have been many new products introduced to the general public during the last few years since Chlordane was outlawed in 1988.
In general the new chemicals have fewer odor problems and can be cleaned up or deactivated with relative ease. Some seem to repel rather than kill termites. Disadvantages are shorter chemical life (more frequent applications necessary). We can no longer rely on an application lasting twenty years or more.

If you need to call in a professional service, look for a company that advocates changes to the house, ie; roof repair; fixing leaks, preventing moisture under the house, lowering the grade around the foundation. Do not be rushed into treatment. Termites work slowly, but they never rest. I am happy to consult with you if you have a termite problem.


For Termite Damage Repairs Contact:
Steve Sproul General Contractor
CA license.#450095
2775 Prosser Rd
Sebastopol, CA 95472
Phone: 707-953-1708

Comments or Questions (I'll give you the straight stuff!) mailto: stevesproul@comcast.net

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