Outdoors

Are you pregnant? Here’s why you likely smell tastier to mosquitoes

A mosquito.
A mosquito. Courtesy TNS

A friend of mine who majored in music was performing an aria at university as part of her final exams years ago.

Although a coloratura soprano, she had the ability to reach and sustain high C. Midway into her recital, she did just that. And while her beautiful voice rang out, a male mosquito flew into her mouth, causing her to cough. Her major professor was going to give her a failing grade for the performance because of the incident.

But I persuaded her that the incident was not the fault of my friend. That sound she produced was quite similar to a female mosquito, and the lusty male followed his instincts down my friend’s throat. The professor relented. The next performance the following week was completed successfully and indoors away from amorous male mosquitoes.

For most of us, attracting mosquitoes is not due to our operatic abilities but because of the way we smell. At least to a mosquito. It starts with a female mosquito detecting the CO2 you exhale. This tells her that you’re an animal and not a plant. She follows the plume’s concentration gradient of carbon dioxide knowing that, at the point of greatest concentration, she might find a suitable host.

Although it may sometimes seem so, not all of the 3,000 plus species of mosquitoes in the world feed on people. There are mosquitoes that feed on birds. There are ones that feed on reptiles. Some are very specific to their host and are more willing to shop around. There are even mosquitoes that feed on other mosquitoes.

We all produce CO2 at relatively similar levels. So, once the female approaches her potential meal, she switches over to detecting other clues. One of these is octenol (a chemical found in breath and sweat). Finally, the mosquito picks out some of the other more than 350 compounds (lactic acid, amino acids, oils) that make up your individual body odor.

Like fingerprints, we each have our own natural odor that can make you more or less attractive to things that want to suck your blood. Enhancing this scent with perfume or cologne seems to increase your attractiveness to mosquitoes. One study published in the British medical journal Lancet found that pregnant women were twice as likely to be bitten as other women.

The study showed that their higher body temperature, combined with their increase in enzyme and amino acid production coupled with their expiration of larger amounts of CO2 during pregnancy, made them more susceptible. Another study produced evidence that people who exercise are much more enticing to the blood-suckers.

You sweat. You produce more heat and oils. You smell tastier. That’s one of the reasons that you’ll new er find me exercising. I get more than enough exercise being a pall bearer for friends of mine my age who start to exercise.

So, what’s the best way to keep from being the target of a hungry mosquito? First, don’t make yourself so attractive. Don’t use perfumes, colognes or aftershaves if your going to be out of doors. Avoid consumption of alcohol. Next, use a good repellent. Repellent is a misnomer.

They don’t repel mosquitoes. They change your flavor. The final clue a mosquito needs is to taste you to make certain that you’re an appropriate host. If you taste wrong, they won’t bite. They know you’re there. They just can’t find you. Eventually, they’ll go and bite somebody else. Repellents containing DEET or Picaridin work well. Cover up where possible. Wrists and ankles are particularly favored targets.

Here are some things not to do. If at all possible, avoid being outside when mosquitoes are most active — dawn and dusk. Mosquitoes have divided up the day and night, with various species available to torment you 24 hours a day. But, dawn and dusk are the peak periods.

Citronella candles produce smoke that hides you from mosquitoes and work as long as there isn’t a breeze. With the slightest puff, the fog is dispersed, exposing you to the hungry hoard. The wristbands sold as repellents don’t work. Studies conducted showed the wristbands gave protection for 20 seconds. The electronic ultrasound devices are fairly useless. In one experiment, the unfortunate graduate student selected as the test product was bitten on the hand that held an ultrasound device.

If, after all of the protective instructions have been followed, you are still bitten, don’t scratch. This will just worsen the irritation and possibly cause an infection. An application of one percent hydrocortisone and an antihistamine is the best treatment for a bite. Apply these as soon after the bite as you can and reapply every 12 hours or so.

Or, if you believe the British Onion Producers Association, you can rub the bite with a sliced onion. One of their scientists claims that the compounds found in an onion will break down the chemicals responsible for the inflammation.

One final thing. Those big lookalikes you see gallumphing about your yard and house are not some sort of mutant mosquito. So, stop sending them to me. They are crane flies and they are harmless, unless you live along the Canadian border. Up there, in large numbers, they cause damage to lawns. Down here, they’re just a bumbling nuisance.

Tim Lockley, a specialist in entomology, is retired from a 30-year career as a research scientist for the U.S. Department of Agriculture. For answers to individual questions, please send a stamped, self-addressed envelope to Tim Lockley, c/o Sun Herald, P.O. Box 4567, Biloxi MS 39535.

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