This is to

scientific Americans 60 Second Science.

I'm Christopher Intagliata.

It might seem obvious that the primary function of insect repellants like Deat

is to, well, repel. But if you bring a pipette tip full of

deat right up to a mosquito as Johns Hopkins neuroscientist Chris Potter did, she just

ignores it. So that really, so that really does demonstrate that, you know, deep by itself, you know, it's not

repellent and it's not going to make them fly away.

Potter's team also genetically engineered

anophiles mosquitoes to make their antennae light up when their olfactory

neurons picked up on a scent. But when they spritz the antennae with

deep and other so-called synthetic repellants, even at 100% strength, there just was no response.

You know, so that was kind of a surprise to us, because going into this, we thought, okay, they're

insect repellents, they're going to activate neurons, that's how they repel mosquitoes.

And so then you know the question is well what are they actually doing?

The researchers kept experimenting with those genetically modified mosquitoes to find out.

A whiff of molecules commonly found on human skin

made the mosquitoes' intenny light up like a Christmas tree, Potter says.

So they do sense us, which you've likely experienced.

But when they combined compounds from our natural human perfume with Diet and other synthetic

repellants, the antennae just flickered dimly.

So these odors which before would strongly activate the olfactory system, essentially

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