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Least-Toxic Control of Termites Choose a different pests

Factsheet: Least-toxic Control of Termites, Taking the Terror out of Termites

Identification

Pest type: Insects

The three main types of termites are subterranean, dampwood, and drywood. All are key beneficial insects in the natural environment, recycling dead wood into reusable nutrients, but become pests when they start recycling your home.

Dampwood termites occur along the Pacific coast from Baja to British Columbia, in parts of Idaho, Montana, western Nevada, and western Oregon, as well as in the cold, dry, high elevations of the Sierra Nevadas, Coast Range, Cascade and Rocky Mountains. They reside in damp and decaying wood. Soil-wood contact often leads to the infestation. They can be identified by the fecal pellets which are about 1 mm long, slightly hexagonal, expelled in sawdust-like piles from the exits of the galleries. If you have the chance to actually see the insect, reproductives are cream to dark brown, an inch in length, and include wings. Workers are about an inch long and white to cream colored. Soldiers are about an inch long with head and jaws that make about a third of their length. They have a large, reddish-brown to blackish head and cream colored body.

Dry wood termites occur from North Carolina, across the southern border of the US, along the California Coast as far north as the San Francisco Bay area and in Hawaii. They reside in dry site, starting new colonies in pre-existing openings in wood. They excavate small nesting areas or galleries and plug the hole for protection from predators. They can be identified by their fecal matter which are tiny, hard, straw-colored pellets with six distinct concave surfaces. If you see them the reproductives are about 1 inch long with fully developed wings usually dark brown. Workers are less than one inch long, wingless, and white. Soldiers are about 5/16 of an inch long, massive brown heads, large mandibles, and lightly colored bodies.

Finally, Subterranean termites occur throughout the US. Their colonies are located in the ground while they forage for food above ground wood. They create mud tubes to travel from underground tunnels to food sources. They prefer moist wood and cork. They have no fecal pellets. If you see them the reproductives are about 3/8 inch long, with long, light grey, translucent wings and dark brown to black cylindrical bodies. Workers are white to grey and range up to an inch long. Soldiers have a greyish white body that is about an inch long with an enlarged cream head, and prominent black mandible.

Is it a problem?

Termites cause billions of dollars in damage each year. They primarily feed on wood, but also damage paper, books, insulation, and even swimming pool liners and filtration systems. Termites can injure living trees and shrubs, but more often are a secondary invader of woody plants already in decline. While buildings may become infested at any time, termites are of particular importance when buying or selling a home since a termite inspection/infestation report is normally a condition of sale. Find out if you have termites before they become too big of a problem.

Pest prevention practices

Remove sources of water/moisture
Remove potential habitat

In-Depth Information:

Pre-construction

SITE PREPARATION

Remove all tree roots and stumps from the building site before starting construction.

Remove grade stakes, form boards and wood scraps from soil before filling and backfilling.

Do not bury wood in the backfill, under porches, steps or patios.

FOUNDATION

Slab-on-ground foundations are most susceptible to termite attack. Termites can enter wood by going over the edge of the slab, through expansion joints, openings around plumbing and cracks in the slab. Monolithic type slab is the best, followed by a supported slab, and then floating types.

A poured, reinforced, crack-free concrete foundation hinders the passage of termites. Termites can go through a crack as small as 1/32 inch

Hollow-block or brick foundations should be capped with a minimum of 4 inches of concrete.

Make certain there are 12 inches of clean concrete foundation between soil surface and structural wood.

Sand grain barriers are effective. When grains are 1.6 to2.5 mm, they are too heavy for termites to move out of theway, and the spaces separating the grains are too small to fitbetween. A 4” layer of sand is required under a concrete floorslab. With crawl spaces, there should be a 4-inch layer of sandaround the interior of the foundation wall and around anypiers. All possible paths between the soil and the wood framing must have a sand barrier.

Termimesh™, a finely woven, stainless steel mesh designed as a barrier for under and around foundations, prevents termites from entering a building. Pest Control magazine (February 1999) reported that after five years of testing, stainless steel mesh remained 100 percent successful as a barrier to subterranean termites.

Steel termite shields prevent termites from enteringthrough the interior cracks of masonry walls or foundation blocks. A good metal shield placed on top of foundation and piers may prevent mud tubes from reaching thewood above them, but will more likely cause termites tobuild around the shield, making their mud tubes easilydetected and destroyed.

VENTILATION

Create ventilated spaces between the ground and any wood structure.

Cover earthen crawl space floors with a vapor barrier –sheets of polyethylene (available at any home supply store) that cover all exposed areas, keeping moisture and dampness at the ground level instead of infiltrating the crawl space. The plastic is usually covered with sand or fine gravel to protect it from punctures when it is walked upon. It should be sealed around the perimeter to the foundation wall, and at any seams, with long-lasting caulking or mastic.

If you vent your crawl space, be sure it has two, if not four, ventilation openings within 10 feet of the corners to provide for cross-ventilation. Vents should be opened in the winter and closed in the summer to prevent moisture problems.

BUILDING

Build with termite-resistant materials, such as concrete and steel.

Unfinished wood can be protected from termite attack by treatment with boric acid (Bora-Care®, Jecta®). Applied as a water solution by dipping or spraying the wood, it will penetrate deep into the wood, and act as an alternative to the afore mentioned barriers.

Do not place basement partitions, posts, or stair stringers until the concrete floor has been poured. No wood should ever extend into or through concrete.

Avoid using styrofoam insulation in the soil adjacent to foundation and basement.

SOIL GRADING

The finished grade outside the building should slope away from the foundation for good water drainage. In the final grading, allow a minimum of 4-6 inches of clearance between the top of the ground and the bottom edge of the veneer.

Post-construction

Fill cracks or voids in concrete or masonry with expanding grout or high-grade caulk, and also caulk around sinks and bathtubs.

Install fan-powered kitchen and bathroom vents to control moisture.

Eliminate dampness - remove or fix sources of water, such as leaky pipes and plumbing, leaky irrigation systems, and improper guttering and siding, and repair leaky roofs.

Replace rotten or damaged wood using naturally insect resistant wood.

Cover exposed wood with paint or sealant.

Screen windows, doors and vents with 20-grade mesh screen.

Ensure good drainage away from the house – point down-spouts or gutters away from the structure, into storm sewers or a drainage well.

Cultural practices

Eliminate all earth-to-wood contact, including mulch, scrapwood, lumber, fence posts, trellises, shrubbery, tree branches or stumps, and firewood that come in contact with the house.

Trim or eliminate shrubbery that blocks airflow through foundation vents.

Move any soil or compost piled up next to the house at least 10 feet away from the structure.

Keep planter boxes built on the ground at least four inches from the house.

Monitoring and record-keeping

Monitoring for termites is absolutely essential to any effective control program. What you are looking for varies with the termite type. However, if every so often you break out your Dick Tracy overcoat, your Inspector Gadget tools and your magnifying glass, you can nip any new infestation in the bud and make repairs to prevent an impending onslaught.
Dampwood termites hide themselves to prevent moisture loss, and are hard to spot. The most obvious sign of termite activity is swarms coming from the home, usually on warm evenings in late summer or fall, especially after rain. (Carpenter ants usually swarm in late spring.) A thorough visual inspection of your house may reveal an infestation in the works. Look around and under the house for damp or damaged wood with holes or tunnels and wood that sounds hollow or soft when tapped. Use a screwdriver or pick to pry into suspicious areas and open up holes. Keep your eyes open for piles of sawdust and dead insects and any conditions that may be promoting moisture or wood decay.
Drywood termites can be difficult to detect, as they live almost entirely inside wood. Look for discarded wings left behind after swarming, fecal pellets, and blistered, hollow-sounding wood. They are distinguishable from their look-alike ant friends because ants have elbowed antennae, a narrow “waist” and a dark spot on their wings. Clues in your case against the subterranean termites may include piles or droppings of sawdust, dead or alive termites, swarms (usually in the spring, beginning in mid-March and through May, after a rain has softened the ground), discarded wings, mud tubes or mounds, and wood damage. Your screwdriver or pick may come in handy to detect damaged wood and con- firm your suspicions. Regularly inspected solid wood or corked hollow stakes in your yard can alert you to activity that may require attention.
Specially trained dogs can sniff and listen for termite infestations, even in hard to reach areas.
Fiber-optic scopes can provide views or hard to inspect areas, such as behind drywall and paneling. If you are not sure that you have an active termite infestation, arrange for a thorough professional inspection, including a written report noting the location of damaged areas, a diagram of the structure indicating the location of the damaged areas, a description of where and how many treatments will be made, and an estimated total cost of control and labor. Don’t be afraid to ask questions and get a second opinion, but let each firm know that other firms were contacted and the information you already know.

Non-chemical and mechanical controls

For Dampwood and Drywood termites Removal of the infested wood or furniture is the quickest and easiest way to handle a localized infestation. Small pieces of wood containing live termites can be soaked in soapy water to kill the insects. Larger pieces can be taken to a landfill or natural area where the decomposing abilities of the termites are helpful.

Drywood termites can also be treated cold treatment, a temperature altering system that utilizes liquid nitrogen to eliminate drywood termites. It is reported to have a 95-99 percent elimination rate and is a good method for inaccessible. Small holes are drilled into the walls and liquid nitrogen is injected into the infested area, lowering the temperature enough to kill the termite colonies. Small items infested with drywood termites can be placed in a freezer or outside for several days during cold weather.

The Electrogun™ is a device that kills drywood termites using a high frequency, high voltage and low amperage electrical current. It should not be used if infestations are widespread, and is not effective next to metal, concrete, or ground because the current is diverted from the termites. It kills approximately 95 percent of the termites when used properly.

Microwaves are effective as a spot treatment or localized infestations. An unshielded microwave device is used to raise the infested area’s temperature to 190, killing the termites. Your microwave oven will not be effective for small, infested items.

For drywood termites, desiccating dusts, such as diatomaceous earth and silica aerogel can be used during new construction or in existing buildings. Choose a desiccating dust that it is not combined with a pyrethrin. Diatomaceous earth must be garden/food grade, as swimming pool grade is associated with lung disease and ineffective at controlling insects. Desiccating dusts abrade the outer shell of the termites, causing them to dry out and die. They are also inorganic and not subject to decomposition, and should protect wood against termites for the life of the building. Avoid breathing in desiccating dusts, as they can cause lung irritation, and always wear a mask and goggles when applying.

For subterranean termites Baiting Systems are the newest innovation in subterranean termite control. They control termites in and around a structure using carefully placed bait stations, which contain a toxicant that is brought back to the colony by the foraging termites. Baits greatly limit the amount of a pesticide used as opposed to the traditional liquid termiticide soil barrier method of control, and decrease chances of exposure to the chemical because the baits are well contained. They are, however, still poisons and should be used with utmost care and only as a last resort. Stations are installed below the ground in the yard, positioned within the structure in the vicinity of active termite mud tubes or feeding sites, or above ground in known areas of termite activity, typically in the direct path of active termite tunnels after the mud tubes have been broken. Baits consist of cardboard, paper or other acceptable termite food that will compete with the surrounding tree roots, stumps, wood piles and structural wood. The toxicant must be slow acting to enhance the transmission of the poison to other termites, including those not feeding on the bait, and to avoid the build up of dead or sick termites in the vicinity of the bait station, which would cause other termites to avoid the area. The least-toxic bait station is Termitrol™, containing boric acid.

For all termites Boric Acid is an effective, least-toxic termiticide. It acts as an effective bait at concentrations of 0.15 percent, an antifeedant at concentrations greater than 0.25 percent, and kills by direct contact with concentrations greater than 0.5 percent. Structural lumber used in new house construction and treated with boric acid is termite resistant; older houses may be made more termite resistant with remedial treatment with borate sprays or by injection into wood already in place. Termites in their galleries are killed when they come in contact with injected borates, and then groom themselves, ingesting the poison. Boric acid kills by inhibiting digestive enzymes and causing termites to starve to death. Bora-Care® and Jecta® are effective products for pre-and post-construction treatments to prevent and control termite infestations; Timbor® is an effect post-construction treatment.

Biological controls

There are several termite killing biological controls that are effective: termiticide Bio-Blast™ contains Metarhizium anisoplae, a common soil-borne fungus, as the active ingredient. The spores from the fungus penetrate and begin to growinside the termite within 4 to 14 days. Bio-Blast™ powder is mixed with water and injected into active termite galleries.
Nematodes, mixed in a water solution and injected into the wood or soil near termite colonies, seek out the termites and destroy them. They will live up to two years. Applicators have reported effectiveness ranging from 50 to 95 percent.

Least-toxic chemical options as a last resort

Boric Acid

Chemicals to Avoid

Look at your product labels and try to avoid products containing those chemicals listed below:

(A = acute health effects, C = chronic health effects, SW = surface water contaminant, GW = ground water contaminant, W = wildlife poison, B = bee poison, LT = long-range transport)

Acetamiprid (A, C, GW, W, B)

Bifenthrin (A, C, SW, W, B)

Chlorantraniliprole (C, GW, W, B)

Chlorfenapyr (A, C, W, B)

Cyfluthrin (A, C, W, B)

Cypermethrin (A, C, W, B)

Diflubenzuron (C, W)

Esfenvalerate (A, C, W, B)

Fipronil (A, C, W, B)

Hexaflumuron (Sentricon) (W)

Hydramethylnon (C, W)

Imidacloprid (A, C, SW, W, B)

Lindane (GW, W, B, LT)

Permethrin (A, C, GW, W, B)

Sulfuryl fluoride (A, C)

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