Most Effective Insect Repellent Ingredients | Deet, picaridin, OLE

When it comes to active ingredients that can keep bugs away, it’s hard to beat deet. It’s “broad spectrum”, which means it works on a wide variety of insects, including mosquitoes, ticks and flies. When scientists test the effectiveness of new insect repellent ingredients, they compare them to deet to see how they stack up.

Deet was discovered in the 1940s essentially by “brute force,” as Matthew DeGennaro, PhD, associate professor in the Department of Biological Sciences at Florida International University, puts it. The U.S. military and the Department of Agriculture jointly screened over 6,000 different compounds looking for ones that would repel mosquitoes. A chemical closely related to deet has been shown to be very effective, then slightly refined to reduce its tendency to irritate the skin. Thus, N,N-diethyl-meta-toluamide, or deet, was born and was finally registered for use in consumer products in 1957.

Although scientists long ago discovered that deet works, they still don’t know exactly why. Theories abound. Deet can mask the smell of humans, confuse the smell-detecting abilities of mosquitoes, or simply cause them to walk away, perhaps because it looks like a naturally occurring substance they evolved to avoid. But it may be more than just a smell at work. According to a 2019 study published in the journal Current Biology, even mosquitoes reared without the ability to smell deet seem to smell the chemical with their feet when they land on it and fly away without biting.

It’s also possible that deet is so effective against mosquitoes because it works on multiple levels and possibly multiple levels at the same time, says Chris Potter, PhD, associate professor of neuroscience at Johns Hopkins University School of Medicine. , specializing in insects. smell.

Why deet also repels ticks is even less understood, although the mechanisms are likely different from those of mosquitoes. Ticks do not have the same odor-sensitive body parts as mosquitoes. Instead, they have a sensory mechanism unique to ticks called Haller’s organ, which we still know very little about, according to Bryan Cassone, PhD, associate professor of biology at Brandon University in Manitoba, Canada. But scientists think it’s the main way ticks perceive their surroundings.

One thing we know: Ticks, which usually hitchhike when you come across them in brush or tall grass, are less likely to attach to your skin if they smell of deet, and they’ll avoid ticks. spots on your skin where the deet is. That’s one reason it’s important to carefully apply repellent to all exposed skin when you want to avoid ticks, Cassone says.