Star-Bulletin Features

Friday, June 29, 2001

Terror of TERMITES

Termiticides and better home
design can help protect your home
from the wood-eating insects

By Tim Ryan

It's not that the little buggers want to force us out of our homes; it's just that they're hungry and, well, wood is what they really like to eat. That's the good news; imagine, voracious as they are, if they liked to eat us.

But there are measures we can take to hinder their appetites, including building better-designed homes.

Remember that Hawaii is paradise for termites because of the year-round warm, moist climate. Termites are the most harmful insects in Hawaii, causing more than $100 million worth of damage each year.

Hawaii's major wood-eating nemesis is the Formosan subterranean termite, a Chinese native that flies, swarms in vast clouds and munches through concrete, bricks or mortar to reach wood, chewing through many other materials, including insulation around underground electrical lines, and causing power outages.

The queen in her nest.

Authorities in New Orleans blame termites for causing $300 million a year in damage in the French Quarter. The city and other groups are spending $100,000 per city block to rid the area of the persistent pests.

There's no way to eliminate termites in Hawaii because the forests are filled with the creatures, said Julian Yates, a University of Hawaii Extension specialist in urban entomology.

"Termites are cryptic in nature," Yates said. "They're hidden, and the only time you know about them is when you lean against a wall and fall through." That's one reason consistent treatment is necessary.

"But you can pretty much eliminate termites from around your home with a baiting system or spraying the soil," he said. Fortunately, termites are unable to develop a resistance to pesticides, and when the queen dies, the colony perishes as well.

A tree branch showing "galleries" through which
termites tunnel for more food.

Termites have been known to nest 20 feet below the ground, though Yates estimates that in Hawaii the depth is more likely to be 10 feet or less. Colonies here average 3 million to 5 million members, though some have reached 10 million, he said. "In a typical Hawaii neighborhood, one colony can be dining on several homes," Yates said. "They build tunnels to find a food source like your house."

There's no reason to give up.

Science may be savior

"Anyone can control termite problems because the technology is there," Yates said. Bait systems, specifically Sentricon, he said, have been shown to be successful, though a newer product, Termidor -- with treatment available through most pest-control companies -- is effective in a different way.

"Termidor looks very promising," said Ken Grace, a University of Hawaii professor of entomology.

Sentricon takes advantage of natural termite behavior. Worker termites constantly forage for wood to feed their colony. When they find food, used in the monitoring device in a Sentricon station, they leave special scent trails to summon their nest-mates to the food source.

Sentricon "stations" are placed in the soil around the structure. The stations are checked regularly for termite activity.

When termites are found in one or more stations, they're transferred to a Baitube device containing Recruit II termite bait. The device containing the termites is then placed back in those stations.

A termite nest inside a hollow wall.

The captured termites feed on Recruit II, tunnel out and send other colony nest-mates back to feed on the bait. As they do so, the colony starts to decline and will eventually be eliminated.

After a colony has been eliminated, the bait is replaced with new monitoring devices.

But the baiting system's basic weakness is that termites must find the bait first, Yates said. Some scientists believe the baiting system is a "colony elimination system," while others call it "a colony suppression system," meaning not all the termites are killed, Yates said.

"There's been no way to determine if you kill all of them," Yates said.

Termidor represents a new class of chemistry that reportedly provides 100 percent control of termites in three months or less and lasts for five years. It is the only termiticide that controls termites by both ingestion and contact, Yates said.

Termidor, which is sprayed directly on the soil and around foundations, has a unique "transfer effect," Yates said. Termidor has been sold commercially in Hawaii for only a year but has been field-tested on four islands the last three years, Grace said.

Soldiers of Hawaii's termite species.

"Termidor is sort of unique because in the three years we've tested it, it appears to perform just as well ... whether it's been an extremely dry area on Maui or a wet area on the Big Island.

"Usually most insecticides at a wet location will wash away or get broken down by water and heat, but Termidor has held up very, very well."

Termidor kills termites within two days of the insects coming into contact with it, Grace said. "So we know that the effectiveness of Termidor lasts a long time and will kill termites for a long time," he said.

Termites unknowingly eat and touch the chemical as they move through a treated area. Because Termidor's active ingredient clings to the termite's body, termites transfer lethal doses to other termites when brushing up against them or sharing food.

Termidor's active ingredient, fipronil, works by interfering with the passage of chloride ions through a receptor in the termite's central nervous system. Fipronil blocks and switches off nerve impulses, severely disrupting the termite's central nervous system and causing death.

Galleries in a wood beam.

Termidor was discovered in 1987 by scientists with Rhone-Poulenc and is the property of Aventis Environmental Science. The chemical compounds of Termidor's active ingredient are predominantly sulfur-based.

According to the manufacturer, Termidor is one of the most tested termite solutions in history. For six years, USDA-Forest Service ground board and concrete slab trials in four states tested Termidor. At every application rate and every last location, it proved 100 percent effective. However, commercial testing has only been conducted for one year.

Termidor is effective at low application rates. Typically, when a pest control professional applies Termidor, the active ingredient fipronil will be just 0.06 percent, much lower than old-fashioned termiticides and less than most insecticides.

Termidor also binds to the soil, so there's no leaching through rainfall or irrigation, the UH scientists agreed.

The cost of treatment for a basic subdivision wood-frame home on a concrete slab is $1,100-$1,200 for Termidor vs. $1,500-$1,600 for Sentricon, which also involves the purchase of annual service contracts ranging from $400 to $600 for maintaining the bait traps.

Protection built in

Besides chemical treatments, homeowners can also design their homes to better resist insects.

The termite-resistant house would be steel-framed with steel posts and pillars and not resting on a slab, Yates said. The garage -- attached or not -- would have a basaltic termite barrier under the concrete slab and perhaps even another barrier called Termi-Mesh.

According to Yates, the basaltic barrier is a 4-inch layer of a granular material between the building and the ground. At least 60 percent of the barrier's granules must have at least one dimension measuring 1.7 to 2.4 millimeters. The granules should be hard and dense to form a barrier that the termites cannot move or chew through.

Soldiers up close.

The method is a cheap and permanent alternative to chemical treatment and does not require re-treatments. The basaltic termite barrier (BTB) was developed to prevent Formosan subterranean termite infestations.

Termi-Mesh is a marine-grade 316 stainless-steel wire mesh that protects the foundation and lower structural members of a house or building from termite penetration. The aperture size is too small for the termites to crawl through, and the material is too hard for the termites to chew.

As for wood in the house, sub-flooring and roof materials should be treated plywood.

Some effective treatments for wood would include zinc borate, available in some composite products, and disodium octaborate tetrahydrate, which is popular for pre-treatment of construction wood. With pressure treatment, borates can penetrate hardwood species like Douglas fir very well, an advantage over some other wood treatments.

Worker termite and eggs.

CCA (chromated copper arsenate) is a popular preservative effective against termites as long as the wood is thoroughly penetrated by pressure treatment, Yates said. Hardwood species do not attain the same degree of penetration beneath the surface as other more easily treated woods, such as pine.

A chemical treatment with Termidor around the posts of a termite-resistant home would still be necessary about every three years.

And there are even removable baseboards and wall section panels that can be installed, allowing the resident to make inspections and treatments easier, Yates said.

"Anyone can control termite problems because the technology is there," he said. "You'll either pay for it now, or you'll pay later."

Roof with termite damage.

Keep termites away

Termites are attracted to wood and wet soil conditions so the goal is to keep cellulose-based products away from your house as well as do what you can to keep things dry near the house by taking the following precautions:

>> Keep the house and foundation dry, making sure to caulk around windows and doors. Poor insulation causes appearance of moisture, and termites thrive in moist environments.

>> Keep gutters clean of leaves and debris. Termites use these materials to build shelter tubes connecting their underground colonies to your home.

>> Schedule regular home inspections before you see signs of termite damage. Preventive measures can stop termite problems before they start.

>> Don't place shrubs or other plants near the foundation of your house. Don't put mulch, especially wood chip mulch, next to the house. Don't affix wooden trellises to exterior walls. Keep scrap lumber away from the house. Remove infested trees and stumps. If you have a leaking water spigot/faucet on the outside of your house, fix the leak. Be certain that the downspouts from the gutters drain away from the house. Be certain that the finished soil grade also drains away from the house. Avoid having a sprinkler system that splashes onto your house or a sprinkler system where the emitter heads are nearly adjacent to the outside walls of your house.

>> Slab construction offers many opportunities for termites to gain entrance through expansion joints, cracks and minute gaps around plumbing. Termites will not penetrate solid concrete, but they can penetrate minute cracks. Slabs are not particularly attractive so most homeowners will hide it under carpeting, but carpeting hides cracks that would indicate a vulnerable spot.

Signs your house
may have termites

The following termite signs usually mean that structural damage has already taken place. A thorough inspection by a pest management professional should be the next step in protecting your property:

>> Swarms of flying termites (called "swarmers" or "alates") can occur both inside and outside the house, usually in the spring. The swarmer termites usually shed their wings after swarming, leaving behind small, papery piles of wings on windowsills, countertops or floors.

>> Small piles of wood residue or shavings often indicate termite activity. Tiny holes in wood, crumbling drywall and sagging doors are other symptoms of wood damage from termites.

>> Termites may make underground tunnels or above-ground "shelter tubes" of mud, feces or debris as a way to search for new food sources and to connect their underground nests to the food. Beware of bubbled paint or visible, pencil-size mud tubes running across concrete or connecting soil to wood. These mud tubes are the tunnels that allow termites access into your home.

Information from the National
Pest Management Association

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