(BBC) — The widely used insect repellent Deet appears to be losing its effectiveness against mosquitoes, scientists say.
Researchers from the London School of Hygiene and Tropical Medicine say mosquitoes are first deterred by the substance, but then later ignore it.
They say more research is needed to find alternatives to Deet, which was first developed by the U.S. military.
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The research was carried out on Aedes aegypti, a species of mosquito that spreads dengue and yellow fever.