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Scientists at the University of California, Riverside have identified a cheap and highly effective way to kill western termites by luring them to insecticides rather than tracking them in every hiding place. In experiments related to research, Journal of Economic EntomologyThe research team used pinene, a pleasant-smelling compound released by forest trees, to move insects toward the treated wood. As a result, the mortality rate was significantly increased from approximately 70% when using insecticides alone to more than 95% when pinene was added.
“We saw a significant difference in mortality rates when using insecticides alone and when using insecticides and pinene together,” said Dong-Hwan Choi, a UCR entomologist who led the discovery. “Without pinene, the mortality rate was about 70%, but with the addition of pinene, it increased to over 95%.”
Why are Western termites such a problem?
Western xeric termites are native to North America and play a real role in nature by helping break down dead wood above ground with the help of microorganisms in their guts. “They’re recyclers,” Cho said. “And they’re very common.”
When the same insect moves from dead trees to houses, its ecological role becomes a serious headache. Concerns persist in places like California and Florida, as well as parts of Canada and Mexico, because they don’t differentiate between natural and structural wood. “Especially in warmer parts of the state, it’s only a matter of time before termites attack your home,” Cho says.
Limits of fumigation
One of the most widely used treatments for drywood termites is fumigation. This involves sealing the house under a tent and filling it with gas to kill insects. California relies more on this approach than any other state in the U.S., according to the University of California, Riverside.
However, fumigation also has drawbacks. Sulfuryl fluoride, a chemical used in fumigation, is toxic to humans and acts as a greenhouse gas, forcing the industry to find alternatives. It’s also expensive and won’t prevent you from re-infesting your home later.
“Even if it’s very thorough, it can quickly re-enter the house even after the fumigation is complete,” Choi said. “Some people fumigate every three to five years because they can’t protect the building from future infestations.”
How pinene enhances the effectiveness of insecticides
Another option is local injection. With this method, pest control workers drill holes into the termite-infested wood to reach the termite “pathways” or hiding places and inject the insecticide directly inside. Because local treatments cover a smaller area, they use fewer chemicals and are less expensive than fumigation. It’s also possible that treated wood will be better protected from future infestations.
“This is a more localized treatment and is, in theory, a better strategy if you want to control drywood termites with fewer chemicals. It’s also less expensive and the treated wood may also be protected from future infestations,” Choe said.
The big challenge is finding where the termites actually are in the tree. These insects can spread through complex tunnel systems, and standard contact insecticides are only effective if the termites come into physical contact with the treated area. So Pinene changed the equation. This scent appears to attract termites from a distance, reducing the need to pinpoint every hidden pocket before treatment.
“Even at low concentrations, pinene is excellent at attracting termites from a distance,” Choe says.
“We don’t think it functions as a pheromone,” Choi said. “We think scent is more connected to their food. Nice scent…dinner time! That’s the concept we had in mind.”
Pesticides used in the study
The insecticide used in the 2024 study was fipronil, which is also used against ants. Fipronil can harm aquatic insects and pollinators if it leaks into the environment, but in this case it was injected into the wood, making it less likely to have unintended effects.
Choe’s lab focuses on how urban pests communicate chemically, with the goal of turning that knowledge into smarter control strategies for pests such as the western termite.
“Our study shows that understanding insect behavior better can be interesting in its own right,” Choe says. “And it also has important implications for more effective pest management, allowing us to use less chemicals without compromising efficiency.”
