BLACKSBURG — A study published May 28, 2026, in the Journal of Experimental Biology found that yellow fever mosquitoes can learn to associate the insect repellent DEET with food and overcome its repellent effect. In experiments, trained mosquitoes attempted to bite a hand sprayed with DEET-containing repellent, while untrained mosquitoes avoided it.

Researchers housed female Aedes aegypti mosquitoes in a central container connected to two flasks—one containing clean air and the other DEET. The mosquitoes were allowed to feed on blood from an artificial feeder while exposed to clean air for 10 seconds, then exposed to DEET in an effort to condition them to link the chemical with a blood meal. In another phase, over 60% of mosquitoes returned to a mesh previously associated with blood feeding when only the smell of DEET was reintroduced, even without blood present.

The study also tested DEET’s association with sugar feeding and found that mosquitoes avoided sugar treated with DEET unless previously trained to associate DEET with a food reward.

“And [mosquitoes] can be trained to be attracted to it by offering a reward with it,” said Anandasankar Ray, a neuroscientist at the University of California, Riverside. Ray noted that mosquitoes also smell with their legs and could not land on the DEET-treated hand in the experiments, suggesting that DEET contact would act as a punishment rather than a reward.

Clément Vinauger, a neuroethologist at Virginia Tech, emphasized that DEET remains effective when used properly. “It’s still the gold standard in terms of protection,” Vinauger said. He also noted, “There might still be some traces of DEET on the skin, but maybe not enough to create that repellency effect. Mosquitoes might still land, drink some blood and not be repelled.”