6. The Life of a Mosquito, In General
I am a mosquito. I am born as an egg that hatches into a larva. (Mosquito people call larvae “wrigglers.”) Then I become a comma-shaped pupa, then I hatch, then my exoskeleton hardens, then I fly. If I am a male mosquito, I eat nectar. I am attracted to individual females by the sound of their wings—a nice wing sound makes me crazy for mosquito sex. But humans do not interest me, no matter what. I can get no nectar from humans, and I am not interested in blood. I live for one week, get laid, and die.
If I am a female mosquito, I eat nectar and take blood for my eggs. I can live longer—months. No matter what kind of mosquito I am, I lay my eggs in water. I might prefer clean freshwater, or saltwater, or brackish water, or water that is polluted, containing more bacteria, frankly. Where I lay my eggs is a matter of species preference and personal preference. I might end up in water the size of the pond in Central Park, or the top of a Snapple cap on 23rd Street. But any water will do. And then I feed. As an average mosquito, in an average human blood heist, I take away about three times my own body weight in blood.
“They’re hunters,” says Leslie Vosshall, the Robin Chemers Neustein Professor at the Rockefeller University of New York, an expert on the science of smell and someone who is not afraid to put her arm into a chamber of mosquitoes and get bitten a lot. “And they’ve adapted to be very sensitive to the smell of their prey, be it birds or humans.”
The cells that transmit scent to the mosquito’s brain have the same shape and structure as those in the human nose, but are shoved into antennae and are more sensitive to odors. And they do have preferences: In some cases, “one individual will attract 90 percent of the mosquitoes and another only 20 percent,” says Vosshall, though we don’t yet understand why. “They are sensitive to human skin odor in ways that are unimaginable to humans, so we can just expose them to a one-by-one-inch square of human skin in the lab and run some air over it, and the mosquitoes will just go wild.”
What happens to a mosquito in this state of aromatic frenzy? It unsheathes its beaklike proboscis, preparing to penetrate the skin of its victim. The proboscis contains six separate tubes and stylets. It begins a complicated process of fluid dynamics such that chemicals are injected, fluids withdrawn. Put another way, it sucks and spits. Among the stuff injected is an anti-coagulant saliva, to ease the extraction, and a painkiller that gives the mosquito time. In that time, the bug inserts and withdraws its proboscis repeatedly, searching in the flashy darkness for a capillary, which, when found, is probed, as if the mosquito were conduting a teeny-tiny angiogram.
8. The Rats of the Air
Mosquitoes aren’t just irritating—they’re not just about stinging and itching and buzzing in your ear. (The theory about the buzzing, by the way, is that they fly toward the ceiling of a room, tracking the carbon dioxide, then dive down to sting, passing an ear.) They are one of the deadliest creatures in the world, killing over 1 million people a year via disease. They carry at least five forms of encephalitis—Eastern equine, Western equine, Japanese, La Crosse, and St. Louis. They also carry dengue fever, yellow fever, Rift Valley fever, malaria, and West Nile virus.
Mosquitoes spreading yellow fever took out one ninth of the population of New York in 1702. In 1793, when Philadelphia was the U.S. capital, 5,000 people out of a population of 45,000 died. Yellow fever struck the United States repeatedly in the eighteenth and nineteenth centuries. Memphis suffered terribly in 1878, with as many as 150,000 deaths. “A lot of people think of mosquito-borne illness as something from another country,” says Joseph Conlon, a former naval entomologist, now technical adviser to the American Mosquito Control Association. “But we had about 128,000 malaria cases annually up until 1935.”
9. The Mosquito Moment
West Nile Virus entered the U.S. in 1999, landing first in Queens. It was brought by Culex pipiens. Between August 12 and August 23, 1999, six people were admitted to Flushing Hospital with similar symptoms—high fever, altered mental state, and a headache. In three weeks, three of the elderly patients died.
West Nile is an odd virus. It may not infect you, and you may have picked up an immunity after a decade of living around it—maybe getting infected by a pipiens, perhaps thinking you had the flu. Eighty percent of people infected will feel fine; close to 20 percent may have flu symptoms. But one out of every 150 people will suffer from tremors, convulsions, muscle weakness, vision loss, numbness, and paralysis. They may end up in a coma, and the neurological effects can be permanent. In other words, West Nile can kill you.