How mosquitoes find you

Original post:  Jul 17, 2015

Summer brings warm weather and opens up many more outdoor activities. Unfortunately, that also brings biting insects.

Full disclosure:  I despise mosquitoes. While I am sure there aren't many people who are fond of them, I myself will go to great lengths to avoid any contact with the bloodthirsty creatures. While some people can tolerate their bites better than others, I find that the welts left behind after their meals will linger and itch for days afterwards. Just being around them is enough to set me on edge.

One of the oddest sensations in recent memory was a trip to Disney World. At the conclusion of the fireworks display at the end of a very long day at the Magic Kingdom, we were unable to take the monorail back to our car because the system was down for maintenance. We had to take the ferries across the lake. On the ten minute ride, there were countless numbers of mosquitoes clustered above us on the ceiling hiding in the shadows. I stood the entire time watching and swatting as they would stealthily swing past me. Let's just say that I was extremely glad when we reached the far shore.

This article from the BBC discusses some new research into how mosquitoes locate their prey. The greater hope is that this new understanding will help to develop better traps in the future.

New research suggests that mosquitoes track down something to bite using a sequence of three cues: smell, then sight, and finally heat.

Biologists recorded the movement of hungry mosquitoes inside a wind tunnel.

The insects were instantly attracted to a plume of CO2, much like a human breath; after sniffing this gas they would also home in on a black spot.

Finally, over much shorter distances, the mosquitoes were also drawn towards warmth.

The findings, published in the journal Current Biology, build on previous evidence that smell is crucial for mosquitoes to pinpoint their next meal.

Body odour, for example, may play a role in how they choose one victim over another.

But mosquitoes are particularly good at sniffing out CO2, which is highly concentrated in the breath of the animals whose blood they feed on - like humans. Mosquitoes can home in on stale, exhaled air from up to 50m away.

It was also known that heat and vision could be important for attracting the blood suckers, but the new study is the first to unpick the distinct role of all three cues.

"We were able to put together a working theory for how all these senses work together in the mosquito, to find a human," said first author Floris van Breugel, from the California Institute of Technology.

In short, this is how it works:

All together, the team developed a three-stage picture of the mosquitoes' hunting strategy:

• From distances of 10-50m they use smell, particularly CO2
• If already aroused by a smell, they will head for something visually interesting - this has a range of 5-15m
• Once within 1m of a potential target, they zero in on body heat

It's also really difficult to avoid these nasty creatures: 

"The unfortunate conclusion is that it's very difficult to escape mosquitoes.

"If you were able to capture all the CO2 that you were breathing out, then it'd be less likely that a mosquito would find you. But then if you were in a group of people, and somebody else wasn't taking those precautions, then a mosquito would follow their CO2 plume. And it may end up finding you before it finds your friend.

"So you'd want to be visually camouflaged [as well]. The more of those sensory cues that you disrupt, the less likely they are to find you and bite you."

Here is the link to the full article:  How mosquitoes zero in on warm bodies - BBC News