Do Termites Come Back After Treatment?

Yes, termites can return after a professional treatment, and when they turn up in the year after a liquid treatment, it usually means they found a way around it rather than that the chemical wore off. University of Kentucky entomologist Michael Potter writes that liquid termiticides are supposed to control termites for at least five years when applied according to the label, and that termites still swarming and infesting a house the year after treatment have found an untreated gap. Bait systems run on a slower clock, measured in months.

Why termites return

Four causes run through extension and agency guidance, and each points to a different fix.

A gap in a liquid treatment. A soil treatment protects only where it is continuous. Potter attributes activity in the year after treatment to an untreated gap, not to breakdown of the product. The University of Georgia’s termite bulletin reaches the same conclusion for recurring infestations after a liquid treatment: the treatment failed to reach the places where termites enter.

Colonies outside the treated zone. University of Florida researchers note that a correctly applied non-repellent liquid can protect the structure, yet it is unlikely to eliminate termite activity in the surrounding area. Colonies nearby survive and keep foraging.

A bait that has not finished working. In a bait system, termites must find the stations first. Potter writes that this may take weeks or months, and control takes months more. The bait kills workers when they try to molt, and UF/IFAS puts the time needed for all the workers in a colony to molt and die at about 3 months.

A treatment that aged or was disturbed. Soil-applied termiticides degrade as they age, according to the Georgia bulletin, which is why most companies require a “booster” treatment before extending a contract past its term. Changes around the house can also break a treated zone; HUD’s builder’s guarantee form for new homes, for example, excludes landscaping and mulch changes that disturb the treated area. EPA’s consumer guide warns that a termite guarantee may become invalid if the owner alters the structure without telling the company first.

Are swarmers after treatment a bad sign?

Not necessarily. The Georgia bulletin says it is not uncommon for swarms to occur in infested buildings after a liquid treatment. No scientific study has examined why. The bulletin reports anecdotal evidence that such swarms may reflect a successful treatment, or a response to the water used in the application, and advises that any swarm be followed by an inspection.

Most winged termites die within a day or so of swarming, the same bulletin notes. Killing them does nothing about the colony that produced them, as Mississippi State University Extension points out. Swarmers that keep emerging from the house in a later season are a different signal, covered below.

How to tell whether the treatment worked

Judge by what does not appear over time. The Georgia bulletin lists three signs that termites have returned:

continued swarming from the structure;
newly built shelter tubes, the mud tunnels subterranean termites travel through, on or in the structure;
live termites in any wood in or on the building.

A lack of swarms alone does not prove control, the bulletin notes. The absence of swarms together with no new tubes and no infested wood is what counts as evidence of a successful treatment.

Two habits make that judgment easier. Keep the treatment diagram and a record of where old tubes and damage were, so that new ones stand out. And keep the inspections going: the Georgia bulletin advises owners whose contract lacks an automatic annual inspection to request one in writing each year.

What a warranty covers if they come back

That depends on the kind of agreement. North Carolina’s Department of Agriculture describes three:

Re-treatment only. The company treats again if termites are found during the agreement period. The department describes this as the usual practice in the industry. It does not obligate the company to repair damage.
Re-treatment and damage repair. The company repairs, replaces or corrects damage up to a stated amount. Not every company offers it, and the structure typically has to meet conditions to qualify.
No guarantee. The treatment is sold without ongoing coverage.

The department adds that these agreements are not an assurance that termites will not return; they provide for the corrective action written into the agreement.

Repair agreements carry a practical hurdle. Because the age of termite damage cannot be determined accurately, the Georgia bulletin explains, a claim usually requires showing live termites at the damaged spot. Photographs or video help, and the company may verify the termites itself. Hidden damage uncovered without live termites, for example during a renovation, is usually treated as old and excluded. Damage recorded at the first inspection is generally not covered, even if termites later return to it.

What some states require in the contract

Several states spell out what a termite contract must contain, which gives any owner a checklist:

Florida (Rule 5E-14.105) requires a written contract before any work, stating the conditions under which re-treatment for reinfestation will be made, the conditions for any repairs, whether reinspections are included and at what intervals, and a signed report after each reinspection.
Texas (4 TAC §7.174) requires disclosure documents with each written estimate, including a diagram of the structure to be treated, the label of any pesticide recommended, the complete details of any warranty, and the termiticide concentration or minimum number of bait stations.
Louisiana (LAC 7:XXV.119) requires contracts on a form provided or approved by its Structural Pest Control Commission that guarantee performance for at least one year and provide for at least one inspection before the agreement expires.
Georgia, according to the UGA bulletin, requires each contract to state the type of treatment, the effective date, a diagram of infested areas, the terms of any guarantee, the conditions for renewal, what happens if the structure is altered, and a three-day right to cancel.

Where a contract lacks these items, the state’s pest control regulator can say what it should contain.

When to call a professional, and what to ask

Call the company that holds the contract as soon as new mud tubes, live termites in wood or winged termites coming out of walls, floors or ceilings appear. An inspection comes before any new treatment. Without a contract, a company licensed for termite work in your state can inspect. Questions worth asking:

Where do you think the termites got past the treatment?
Will the re-treatment use a different approach? The Georgia bulletin suggests owners ask for new drill-hole placement under slabs, or foam applied into voids, when a first attempt fails.
For a bait system, when were the stations last checked, and which ones show activity?
Is this covered under re-treatment only, or under repair terms as well?
Do you need to see live termites before accepting a repair claim, and how should I document them?
When is the next inspection, and will I receive a written report?