Then, as now, mosquitoes developed in standing water. And all too quickly: The blood-sucking insect can grow from an egg to an adult in just five days—and the eggs are plentiful. The malaria mosquito lays several hundred of them, one by one; other species drop rafts at a time. Their nursery-cum-swimming-pool can be as small as a discarded paper cup or a jar top, and it can be very polluted—pure sewage will do. A bristly mosquito larva, about 8 millimeters long, resembles an aquatic wirehaired dachshund or, if you prefer, a hairy maggot. Its head hangs down with its body suspended from the water surface by a breathing tube. As the snorkel takes in air, brushes filter the water for protozoans and bacteria.
A New Zealand mosquito has a mating habit that is the very definition of rapacious. Once the larvae have developed into comma-shaped pupae, adult males start to hang around, waiting for new females to hatch. As soon as one emerges, a male pushes in beside her and mates before her wings are dry enough to help her escape. A more common, and more voluntary, mosquito mating ritual has the males gathering in a cloud. The females choose to fly into the party.
Our living allies in mosquito control are primarily the fish that eat the larvae stage. Here we can give thanks for piranhas and the aptly named Western Mosquitofish. Dragonfly larvae eat mosquito larvae and dragonfly adults eat mosquito adults. Bats, for their part, have gotten more good press than they deserve. It turns out mosquitoes constitute less than 1 percent of the bat diet. Same goes for the purple martin, though these lovely swallows are nice to have around.
Even if it were possible for bats, birds, and pesticides to eradicate them all—which it isn't—wholesale mosquito slaughter would not be a great idea. Their huge numbers of larvae feed small fish, and those small fish feed big fish, and those big fish are the primary source of protein for much of the developing world.
Naturally, we take an anthropocentric view of mosquitoes. They matter because they are Man's Deadliest Foes. Maybe it's worth thinking of life from the insect's point of view. It's no picnic being a female mosquito, for the three to six weeks she lives on this earth. Drinking blood isn't easy; the longer the little phlebotomist has to poke for a blood vessel, the greater her chance of getting squashed. And after all, she didn't choose to carry all those deadly parasites. Where does she pick them up? From us.
We've spent the past 50 years trying to find a malaria vaccine for humans, so we don't give malaria to mosquitoes or contract it from them. It may make more sense to help the bugs out instead. We've recently sequenced the genomes of two of the most dangerous kinds of mosquitoes. Instead of using this knowledge to wipe them out more efficiently, what if we used it to strengthen their immune systems? We could live with the welt and the itch as long as we knew we weren't going to get the fevers.