Eliminating an infestation of Formosan subterranean termites (Coptotermes formosanus) typically requires an in-ground or above-ground solid bait application, which can present an inconvenience to homeowners, particularly when baits must be placed inside the home. A newer method in development uses a fluid formulation of a similar bait that can be injected into infested wood. (Photo credit: Scott Bauer, USDA Agricultural Research Service, Bugwood.org)

Any homeowner dealing with a termite infestation wants to be rid of the problem, naturally, as fast as possible. A liquid insecticide applied where termites appear can eliminate them, but it typically won’t eliminate an entire colony, which could be as far as 300 feet away from the home. A termite bait, on the other hand, acts more slowly—allowing time for foragers to consume it, carry it back to the nest, and spread it among fellow colony members—but is more likely to fully eliminate the colony. These solid baits are typically placed in in-ground stations that must remain in place for several weeks or months before being consumed by termites. Above-ground stations are placed on top of active infestation for immediate consumption, but can present an inconvenience to homeowners, particularly when baits must be placed inside the home.

A newer method, however, developed in recent years, looks to combine the advantages of a liquid application with the comprehensive impact of existing baits. Nan-Yao Su, Ph.D., distinguished professor of entomology at the University of Florida, and colleagues have been working on a fluid termite bait since 2011 as the next evolution of the termite bait methods that Su first developed in the 1990s. In June, Su and colleagues shared results of a long-term field test of fluid termite bait in a report published in the Journal of Economic Entomology.

The fluid bait formulation was a mixture of 10 percent dry bait substance impregnated with hexaflumuron (a chemical that interferes with termite growth, specifically inhibiting synthesis of chitin in the termite’s exoskeleton) and 90 percent fluid cellulose solution. The researchers tested the fluid bait in three trees and three buildings with infestations of Formosan subterranean termites (Coptotermes formosanus). They drilled half-inch-diameter holes in affected wood and used a caulking gun to inject the fluid bait into the tree or wall interiors. Then they monitored the termites’ reaction and the effects on the infestations.

Researchers at the University of Florida tested a fluid termite bait in a field trial reported in June in the Journal of Economic Entomology. Unlike existing solid bait systems, which use in-ground or above-ground stations, the fluid bait can be injected via drilled holes directly into infested wood, using a tool such as a caulking gun. (Image originally published in Su et al 2018, Journal of Economic Entomology)

In all of the test cases, the termite colonies were eventually eliminated. But they varied in the amount of time and bait reapplications needed. One colony was eliminated in four months, while the longest took 22 months. Some tests took just one bait application, while others took as many as 10 or 11. The researchers posit that disturbance caused by drilling and injection caused some of the delayed results, as foraging termites were chased away for a few months before they returned. The varying size of the termite colonies—and thus their alternative foraging options—also could have played a role in the variability.

Su says the results of the study are encouraging and that he hopes the fluid termite bait product could be available to pest management professionals in the not-too-distant future. “We need to do more field trials to make sure we encounter most of the problems we will encounter and solve them first,” he says.

Hexaflumuron is classified by the U.S. Environmental Protection Agency as a “reduced-risk pesticide,” meaning it poses less risk to people and the environment than alternatives. Su cites this as an additional potential advantage of the prospective fluid bait system.

“Termites baits use less-toxic insecticides at smaller quantities than liquid termiticides, hence they have much less environmental impact,” he says. “Yet, more than 50 percent of the termite control today still relies on old liquid termiticide barriers that cannot eliminate termite colonies, and even those that use baits still inject liquid termiticide into active galleries. There are many reasons for this, I am sure, but I hope the introduction of fluid bait will encourage the industry to make the switch, even by just a little.”