How do termite treatments work?

Termite treatments work in the soil, because that is where the termites that damage Virginia houses live. A pro either puts a long-lasting termiticide into the soil around and under the house, so termites tunneling through it die, or sets bait stations in the ground that feed the colony a slow-acting insecticide it spreads through its own nest. Treated building materials and physical barriers are mostly options for new construction.

Why the soil is the target

The most common termite in most of the United States is the native subterranean termite.^[1] It lives underground in colonies, not inside the wood it eats. A colony can hold hundreds of thousands to millions of termites and forage over as much as half an acre, and the colony attacking a house may be in a neighbor's yard.^[3] Workers travel up to the house through the soil and through mud tubes. They usually come in from the soil along the foundation, through cracks in the slab, utility conduits, expansion joints and plumbing connections.^[4]

That is why spraying the wood you can see rarely solves anything. Every treatment below either blocks the path from the soil into the house or reaches back into the colony.

Liquid soil treatments

The soil-applied barrier treatment is the most common technique for treating termite infestations, and the termiticide has to be specifically labeled for that use.^[1] The aim is a continuous treated zone in the soil along and under the foundation. Termites that tunnel into it are killed, and termites already inside the house usually die off as well, because they can no longer return to the soil for moisture.^[2]

Older products mostly repelled termites. Current products such as fipronil, imidacloprid and chlorantraniliprole are non-repellent,^[2] so termites do not avoid the treated soil, and those that tunnel into it are killed.

The job is bigger than most people expect. A typical treatment may involve hundreds of gallons of termiticide injected into the ground along the foundation, beneath concrete slabs and within foundation walls.^[2] It takes masonry drills, large-capacity spray tanks and long metal rods for injecting soil,^[2] and often drilling and injection through porches and patios that touch the house.^[3] Many companies offer a perimeter treatment instead: the whole outside of the house, plus spot work on infested or high-risk areas inside.^[2] Localized spot treatments are usually a gamble, and most reputable firms will not warrant them.^[2]

All liquid termiticides are supposed to control termites for at least five years when applied according to label directions.^[2] If termites keep swarming and infesting the year after treatment, it is usually because they found an untreated gap in the treated soil, not because the product wore out.^[2]

Bait systems

Baits are cellulose combined with a slow-acting insecticide.^[1][3] Foraging termites eat the bait and share it with their nest mates. Within weeks of eating it, termites die while trying to molt.^[3] The slow action is deliberate: it gives the bait time to spread through the colony before termites notice anything is wrong.

The stations are plastic tubes set flush with the ground. Stations are usually set about 1 to 2 feet from the foundation and typically 10 to 15 feet apart around the whole perimeter,^[3] with extras near woodpiles, stumps, damp spots and old damage. Depending on the product and the company, stations are checked monthly, quarterly, twice a year or once a year.^[3]

Baiting takes patience. Weeks or months can pass before termites find the bait, and elimination can take several months or longer.^[3] In exchange, the house is barely disturbed. Floors are not drilled, furniture is not moved, and the technician usually does not need to come indoors.^[3] The catch is that protection lasts only as long as the stations stay in the ground and keep being checked, because no pesticide is left in the soil once the termites are gone.^[3]

Wood treatments and physical barriers

EPA lists liquid soil-applied termiticides, termite baits, building materials impregnated with termiticides, and wood treatments as approved approaches.^[1] Borates are commonly sprayed on framing during new home construction to protect the wood.^[1] Physical barriers such as steel mesh and sands of particular sizes are typically built in during construction.^[1] EPA does not regulate methods that use no insecticide,^[1] so ask any company selling one what evidence it has.

Liquid or bait: what decides it

A good company will explain why it recommends one over the other for your house. The usual deciding points:

• Speed. Liquids act faster than baits. With a heavy infestation or a sale closing soon, that often settles it.^[3]
• Disruption. Baits avoid drilling floors, porches and patios.^[3]
• The house itself. Baits may be the only workable option where there are wells, cisterns, nearby ponds or streams, sub-slab heating ducts, drainage systems or inaccessible crawl spaces.^[3]
• Long-term cost. Compare the first-year price and the yearly renewal; see what termite treatment costs in Virginia.

Some homes get both: baits around the outside and liquid where termites are active.

Safety and what to ask for

Done improperly, a barrier treatment can contaminate the home and nearby drinking water wells and still fail to protect against termites.^[1] Many termiticides are highly toxic.^[1] Ask the company for a copy of the product label before work starts. Ask the applicator how long you need to stay out of treated areas and what to do about pets, food and water supplies. Be wary of anything sold as a termite killer rather than a structural treatment. A product that only claims to kill termites has not shown that it protects a structure.^[1]

This is not a do-it-yourself job for an infested house. Some termiticides can only be used by trained and licensed professionals,^[5] and store-bought products will seldom eradicate an existing termite problem.^[2]

When to call a licensed pro

In Virginia, "No person may apply or recommend for use any pesticide commercially without a pesticide business license and the employment of a certified commercial applicator" responsible for safe application.^[6] Commercial applicators who treat for termites are certified in a separate wood-destroying pest control subcategory.^[7] Call a licensed termite company when:

• Winged termites, or piles of shed wings, turn up indoors.
• You find mud tubes on the foundation, piers or framing.
• Wood sounds hollow or breaks open to show tunnels packed with soil.
• You are buying or selling a house and need an inspection report.
• An existing treatment is due for renewal or termites have come back after one.

Learn the signs of termites in a house, and see how to check a pest control license in Virginia before anyone treats your home. Browse termite treatment services, find pest control businesses around Blacksburg or read more pest control answers. When you are ready, describe the termite job on Loclis so licensed businesses can quote it in writing.