According to a new study, mosquitoes are learning to ignore DEET, the BBC reports.

Researchers at the London School of Hygiene and Tropical Medicine tested the responses to DEET by the Aedes aegypti, a type of mosquito that can carry yellow fever and dengue fever and is thus particularly dangerous to adventure travelers.

In a new study published in the journal PLOS ONE, researchers say that while mosquitoes are at first repelled by DEET's smell, they soon become accustomed to it and can return bite the wearer. Electrodes attached to the insects' antennae show that they adjust to the scent of DEET and simply stop smelling it.

This is something I've heard campers and hikers comment on for quite some time now. Spending time in mosquito-ridden Missouri, I've noticed this trend myself. Missouri has about 55 known types of mosquito, including the Aedes aegypti.

An earlier study has raised questions about DEET being a neurotoxin. It looks like science's next task is to find a better insect repellent.

I've also noticed that mosquito coils, which do not have DEET as an active ingredient, no longer seem to work on Missouri mosquitoes either. I enjoy sitting on the porch swing of my friend's house reading. It used to be that a burning coil set nearby would keep the bugs away. No more. The last time I tried it the little bastards were attacking me so much I actually put the coil under the porch swing so the smoke rose right onto me. The mosquitoes didn't seem to care. I soon retreated inside.


[Photo of Aedes aegypti courtesy US Department of Agriculture]

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