See more Daily Mail on Google - save us as a Preferred SourceBy GETHIN HICKS, REPORTER Published: 00:16 BST, 29 May 2026 | Updated: 01:29 BST, 29 May 2026
Mosquitoes can learn to love the smell of the world's most common insect repellent, scientists have found.DEET, chemically known as N,N-diethyl-meta-toluamide, is used across the globe and has been recommended by the UK Health Security Agency as its first choice to protect against bites. However the new study conducted by American and French scientists for the Journal of Experimental Biology discovered that mosquitoes can, in certain circumstances, learn that the presence of DEET indicates the possibility of a blood meal. The experiment began with a swarm of the insects placed in a fabric mesh enclosure before being presented with a bag of warm sheep's blood to observe how keen they would be to feed on it.The Aedes aegypti mosquitoes were quick to feast on the blood but, initially, when the smell of DEET was introduced, they moved away. Next, the scientists fed the insects warm blood for 20 seconds, releasing DEET during the last 10 seconds. That part of the experiment was repeated three times before the mosquitoes were exposed to solely the scent of the repellent.This time, more than 60 per cent of the insects tried to bite the fabric - even though there was no blood. Mosquitoes can learn to love the smell of the world's most common insect repellent, scientists have foundThen, one of the scientists offered up their hands - one clean, the other coated with DEET - to the trained mosquitoes to see which one they would bite.And the mosquitoes almost unanimously flocked to the hand covered in repellent - in results which were described as 'beyond doubt'. The scientists had similar results when they repeated the experiment using sugar instead of blood, because mosquitoes mostly feed on plant nectar in the wild. Co-author of the study, Clement Vinauger, said: 'The common assumption has always been that repellents work because of their chemistry.'However the scientist said that his latest study reveals that 'it's not the chemistry of the molecule itself which is toxic' to the insects, but instead they are repelled by how they 'interpret the chemical information'. Mr Vinauger, who works with Virginia Tech in the United States, added: 'What we are showing is that the mosquito's brain can rewrite that response based on experience. 'What the insect has learned matters just as much as what the chemical does. That, I think, is the paradigm shift.'The other author, Claudio Lazzari of the Insect Biology Research Institute in France, however insisted that 'very specific conditions' would be required for the findings to be emulated outside of the lab conditions. He added that DEET, which was developed in the US around 80 years ago, remains 'the absolute gold standard for repellents' - and said that his study's findings do not 'call into question the effectiveness' of the repellent.Meanwhile Doctor Nina Stanczyk of ETH Zurich University said the findings showed mosquitoes' impressive capacity for learning. She said: 'Mosquitoes have been shown to have impressive learning abilities, but the fact they can associate such a strong repellent smell with their food and are then attracted to it afterwards is remarkable, and important for us to be aware of for the future.'She nevertheless also emphasized that travellers should not ditch their DEET supplies. 'People should understand that DEET does not lose its effectiveness through normal use, but only under specific laboratory conditions designed to reveal how it works on mosquitoes,' the doctor added.Join the discussionShould we rethink how we use insect repellents if mosquitoes can learn to seek them out?What's your view?
