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By Jill Riddell

I'm invited to a friend's parents' house in Highland Park for a party, so I drive up with my friend Jay, for whom this is practically a wilderness excursion. Since his idea of enjoying nature is to step from his air-conditioned apartment onto the porch long enough for a cigarette, it's unclear how he'll handle a whole evening in a suburban backyard. We arrive in the early evening, while the sun is still warm and the air breezy. After some lackadaisical effort toward mingling, he and I settle into chairs by the pool, where we assume we'll be ensconced for the rest of the evening.

Jay has a list of what irritates him about the natural world, and close to the top is insects. But the air is hot, and we remain untroubled by bugs. Then, after a couple of gin and tonics, the sun drops out of sight, and the wind calms down.

We're still yakking about not much of anything, comfortably sitting in shorts and T-shirts. But around us hundreds of mosquitoes begin to stir in the shrubs where they've been waiting, staying moist, cool, and alive. I've had time since that evening to piece together as accurately as possible the bloodbath that followed, and this is my reconstructed, true-crime-show version of what happened.

The mosquitoes drift out into the open, each intent on accomplishing the next task in its life cycle. Some males visit flowers for sips of nectar, dipping the tips of their proboscises into the fluid and gently inhaling it. Other males head into a swarm that forms over the chimney; once inside, they begin to vibrate violently in preparation for mating. Sometimes a female will venture into the swarm and do it right there and then, but more often a male leaves the swarm and uses his highly sensitive, hairy antennae to track her high-pitched whine. If she's located and receptive, the male flies beneath her and faces her while grabbing hold. They will either stay aloft, performing the act on the wing, or settle on a nearby twig for a few romantic seconds.

The male mosquitoes--which have neither the desire nor the ability to bite us, and so float harmlessly nearby--are intent solely on mating and eating enough to keep them alive until they mate. They die quite soon after their big moment. Happily mated, the female tucks the sperm into a sac in her abdomen, but she has dicey work ahead of her, for she can't develop the eggs until she partakes of a nice meal of Jay's luscious blood.

As he sprawls in the chaise lounge spouting witty repartee, he emits carbon dioxide, the substance mosquitoes use to locate their hosts. Zeroing in on the invisible gas, the first females arrive. As they quiver on his calves and forearms he attempts to squish them, an operation that should be simple given the difference in size between Jay and the mosquitoes. But it's somewhat tricky, because a mosquito's head is almost entirely covered by a pair of compound eyes with an extraordinary range of vision that help it spot Jay's fingers as they approach. And as evening darkens, it becomes harder for Jay to see the little parasites. Some begin to succeed in drinking his blood. Soon the number of mosquitoes grows to the point where Jay's taking pleasure in the gory death of one bug on his arm even as another is sucking on his ankle and another's on the back of his knee. Soon there's a tiny forest of them on his skin.

To describe what the mosquitoes are doing to my unhappy friend as "biting" doesn't quite capture the intricacy of the act. The proboscis of the female is, in the words of J.D. Gillett, author of The Mosquito, "a most complex, delicate and beautiful affair." Beneath a protective sheath is a complicated set of stylets and sensory structures called the fascicle. Surrounding the tubes of the fascicle are two pairs of pointed, serrated scalpels that have evolved over the course of 70 million years until they're absolutely perfect for cutting and piercing Jay's skin.

The female mosquito--let's call her Lisa--lands on the back of Jay's neck. She touches her fascicle to his skin and pierces it with a downward thrust. She continues to apply pressure, and the fascicle, aided by alternating movements of the paired scalpels sinks down into the tissue beneath the epidermis. Once into this tissue, Lisa pulls the fascicle out partway, gathering momentum to jab it in deeper. Then she bends the tip back and forth under the surface of Jay's sensitive skin until she locates and pierces one of his capillaries.

She probes the canal of the blood vessel and begins sucking Jay's body fluids up one tube in the fascicle, while injecting saliva down another. The saliva from some species of mosquitoes acts as an anticoagulant, but its main purpose is to increase the blood supply in the vessel. Lisa uses a pump to draw blood up into her head, then another pump located in her thorax to push it into her stomach.

This specialized operation takes only 40 seconds. Unless Jay manages to kill her in the course of it, she'll consume well over her own body weight before she withdraws and staggers away to the bushes to rest. After a few days her eggs will have matured, and Lisa will fly off again to find a good place to lay the eggs. At this point her eggs are still unfertilized. When an appropriate pool of still water is located--it could be a pond, but it's just as likely to be rainwater puddled inside the curve of an abandoned tire--Lisa releases the male's genetic material from the sperm sac, fertilizing the eggs. Depending on what species she is, she lays the eggs either on top of the water or in the soil just above the waterline.

This evening comes to mind now that a banner year for mosquitoes is under way. According to Khian Liem, director and entomologist for the South Cook County Mosquito Abatement District, Chicago has had twice the average amount of rainfall in the last couple of months, springing free the Aedes vexan mosquitoes, which lay their eggs in soil along riverbanks and ponds. Their eggs can lie dormant for several years waiting for the water level to rise to the point where they're inundated and able to hatch. The relatively cool conditions we've had favor all 40 species of mosquitoes in the area; because mosquitoes are so tiny, they dehydrate easily and die in dry heat.

After the better part of an hour passes, Jay finally tells me he can't stand it. I've heard that some people are more sensitive than others to mosquito bites, but since I'm at the least-affected end of the spectrum, I discount his whining. I'm being bitten too, but not badly, and it seems an acceptable price for being able to sit outside on a warm summer night. I tell him if he doesn't scratch he won't notice them so much.

Several more minutes pass before Jay persuades me he's sufficiently tormented. We enter the house through a bright utility room, where we can see each other for the first time in a couple of hours. On my skin are a few light bumps where mosquitoes have successfully supped. But Jay's legs and arms are covered with pulsing red welts. He looks like he has a big messy case of chicken pox. I'm amazed that anyone's epidermis could react so strongly to mosquito bites. Vindicated, Jay affects a martyred expression as he accepts the host's offer of calamine lotion.

All of this has made me wonder, does Jay disdain the outdoors because he's so reactive to insect bites? It'd certainly make me think twice about going outside if I looked like that when I came back in. Or does his lack of contact with the outdoors cause him to become overly sensitive when he's forced to come in contact with it? All I know is I wouldn't trade skins with him for anything.

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