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New chemical kills 95% of termites without harming humans

Scientists found a way to make termites self-destruct — by preventing them from growing new exoskeletons.

Date:

May 9, 2026

Source:

University of California - Riverside

Summary:

Scientists may have found a smarter, safer way to wipe out termites hiding inside homes. A chemical called bistrifluron prevents drywood termites from forming new exoskeletons during molting, killing entire colonies from within. In tests, it eliminated about 95% of termites while avoiding the toxic side effects of traditional fumigation. Researchers say the method could provide longer-lasting protection as termites spread into new areas.

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FULL STORY

Western drywood termite colony. Credit: Dong-Hwan Choe/UCR

Drywood termites are experts at staying out of sight. They live inside wooden structures, quietly feeding and expanding their colonies where homeowners may not notice them until damage is already underway. But their hidden lifestyle also depends on a vulnerable biological process: molting.

Researchers at the University of California, Riverside have shown that bistrifluron, a chemical that blocks the formation of new termite exoskeletons, can destroy drywood termite colonies by interfering with the insects' ability to grow. The findings were published in the Journal of Economic Entomology. In laboratory testing, the treatment killed about 95 percent of a colony without the mammal toxicity concerns linked to many traditional termite control methods.

A Safer Way To Target Termites

"This chemical is more environmentally friendly than ones traditionally used for drywood termite infestations," said Nicholas Poulos, corresponding author of the paper and a doctoral student in UCR's Department of Entomology. "It's specific to insects and can't harm humans."

The reason the chemical is so targeted comes down to the termite body plan. Humans have bones inside their bodies. Termites wear their support system on the outside in the form of an exoskeleton. That outer shell is built largely from chitin, a tough natural material also found in fungal cell walls, fish scales, and the beaks of squids and octopi.

For insects, chitin is essential. It gives the exoskeleton strength, helps shield the body, and provides anchoring points for muscles. When termites grow, they must shed their old exoskeleton and build a new one. Drywood termites go through this process about seven times during their lives.

Bistrifluron interrupts that step. Instead of poisoning termites in a broad, fast acting way, it prevents them from making the chitin they need for their next protective shell.

"Once the termites reach a certain stage, they have to molt. They cannot avoid that," said Dong-Hwan Choe, UCR entomology professor and senior paper author. "With a lethal dose of this chemical, they'll try to shed their old exoskeleton but won't have a new one ready to protect them."

Termites Spread the Treatment Themselves

The effect is not instant. The researchers saw that bistrifluron first made the termites less active and reduced their feeding. Over time, the chemical blocked successful molting, and the insects died.

The 2025 study tested three chitin synthesis inhibitors against the western drywood termite, Incisitermes minor. Bistrifluron worked faster than chlorfluazuron and noviflumuron at the tested rates. In one no choice test, bistrifluron produced 99 percent mortality over 60 days. In a choice test using a 0.1 percent rate, it produced 96 percent mortality over the same period.

The most important part may be how the chemical travels. After termites fed on treated wood, they passed material to other members of the colony. In transfer tests, even when only 5 percent of termites had been exposed, the groups reached 100 percent mortality by day 90. The study reported that food material moved from exposed donor termites to unexposed recipients within 24 to 48 hours.

That finding fits with newer UC Riverside work highlighting how western drywood termites share food and essential gut microbes through proctodeal trophallaxis, a mouth to anus feeding behavior that is difficult to observe because the insects live almost entirely inside wood. Those hidden social behaviors can make infestations hard to detect, but they may also help treatments spread once termites contact treated material.

"It's been successfully used on subterranean termites, which are also important structural pests," Choe said. "But native western drywood termites are also important, especially in California."

A Slower Collapse With Big Advantages

Once drywood termites consume the treated wood, the compound can move through the colony as termites interact. Full colony collapse takes roughly two months, making it slower than some conventional methods. But the tradeoff could be worth it: lower toxicity, more targeted action, and the pot