Chemical blocks termites’ new exoskeletons, killing 95% of colonies without harming humans

Researchers say they have discovered a chemical that kills 95% of termite colonies while leaving humans unharmed. The compound disrupts the new exoskeleton that termites require to survive their next molt, turning a natural stage in their life cycle into a fatal vulnerability.

The research comes from the University of California, Riverside, where doctoral student Nicholas Poulos and entomology professor Dong-Hwan Choe published their findings in a 2025 study in the Journal of Economic Entomology. The compound, called bistrifluron, is an insect growth regulator that interferes with the formation of a new exoskeleton. In laboratory tests, it produced 95.7 percent mortality when termites had a choice between treated and untreated wood, and about 99 percent mortality when termites were continuously exposed to treated wood.

Termites Hide in Wood They Destroy

Drywood termites vanish into the very material they consume. Rather than constructing visible nests, they can spend almost their whole lives concealed within beams, framing, furniture, and similar dry wood, quietly hollowing out galleries as a colony expands.

That concealed existence makes them hard to find and hard to remove. Standard fumigation and other control methods have limits, and the Riverside team uncovered a biological weakness that termites cannot conceal: they have to shed their skin.

How the Chemical Works

An insect’s body is encased in a rigid outer covering known as an exoskeleton, which serves as its internal skeleton. This outer shell is made from a strong natural material called chitin, which gives it its shape and strength. Chitin is common throughout nature, making up the exoskeletons of insects, fungal cell walls, fish scales, and even the beaks of squids and octopi.

These creatures shed their covering skin seven times across their lives, each time growing a new, larger one. A substance known as bistrifluron works against the manufacture of that very substance, chitin, which the insect needs for its next covering. It does not act like a poison that kills quickly; instead, it interferes with the process of chitin production, leaving the insect unable to make enough of it for the next molt.

“This chemical is more environmentally friendly than ones traditionally used for drywood termite infestations,” said Poulos, the corresponding author of the paper. “It’s specific to insects and can’t harm humans.”

The Treatment Takes Time

The workings behind the process also explain why bistrifluron acts relatively slowly. Scientists first saw drops in activity and feeding. The termites kept moving toward their next molt, yet eventually failed to finish it and died.

The group tested three chitin synthesis inhibitors against termites and found that bistrifluron caused the quickest death at the concentrations examined. In an experiment where the insects had no untreated wood to choose, the 0.1 percent bistrifluron treatment brought about about 99 percent mortality after 60 days. When the termites were given both treated and untreated wood, that same concentration produced roughly 96 percent mortality.

The figures matter because drywood termites are especially tough targets. These termites can live entirely within pieces of wood, unlike subterranean termites, which keep their colonies connected to the soil.

“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.”

Colonies Spread the Treatment

Perhaps the most interesting finding concerned what occurred after just a portion of a group came into contact with bistrifluron. Termites are social insects that commonly share food and other substances. The researchers exposed some termites to the substance and then put them together with untreated members of the same colony. Colored food was used to track the movement of material between individuals.

Within 24 to 48 hours, material from the exposed termites had spread to nestmates that had not yet been treated. Even more strikingly, groups in which only 5 percent of the termites had initially encountered bistrifluron eventually reached 100 percent mortality by day 90. Groups that began with 50 percent exposed termites moved along a similar survival pattern.

A small group of termites could hold enough bistrifluron to help carry an effective dose deeper into a colony.

Feeding Behavior Carries the Poison

Further studies from the UCR group have offered an unusually close look at how these concealed colonies might move substances through their social behavior. In 2026, researchers pointed to images and video that show western drywood termites engaged in proctodeal trophallaxis, a feeding behavior where material is received from another termite’s hindgut. That exchange matters because it passes along nutrients and gut microbes that help termites digest wood.

Typically, that strong social working together is what keeps the termite colony alive. But for pest control, it could work in favor of a treatment by spreading it to termites that never come into direct contact with treated wood.

The Case for a Safer Alternative

These findings point toward a safer path than conventional fumigation. The chemical zeroes in on a process that only insects possess, sparing human beings from any harm. This particularity stems from the biological pathway at its core, and it marks a real step past techniques that poison the air or the wood itself.

Scientists are still running tests in the lab, and the figures come from controlled experiments. The basic idea is set: a chemical that keeps termites from forming a new exoskeleton turns a regular step in their life cycle into a dangerous weakness. The group is already studying how the behavior of these unseen colonies carries the treatment through the wood they occupy.

The UCR researchers have spent years documenting the behavior of these termites, and their 2025 paper is just the first publication in this line of work. The recent images and video of proctodeal trophallaxis show a colony in motion, and the team’s observations of how the treatment moves through a group are a direct extension of that work.

The 95 percent figure grabs attention, but the real story is the mechanism behind it. A chemical that blocks an exoskeleton need not act with speed, because the termites cannot avoid molting. Once they reach a certain stage, shedding their old exoskeleton is not a choice they can avoid — and without a new one ready to protect them, they die.

The social behavior that usually aids the colony’s survival turned into an advantage for the treatment. Just a few exposed termites can carry a lethal dose to the rest of the colony, and the team’s recent images and video of proctodeal trophallaxis show precisely how that exchange occurs.

The termites cannot escape their own biology, and the researchers have found a method to exploit it without harming humans. This is clever science.

Source material: “New chemical wipes out 95% of termites without harming humans,” ScienceDaily.

environmental science · insect biology · pesticide · termite control · UC Riverside