We squash mosquitoes with our enormous hands. We poison-bomb them from spray trucks and airplanes. We irradiate them, drain their habitats, breed them experimentally in laboratories to confound their DNA. We’ve known for more than a century that a mosquito’s bite can pass on brutal disease: Zika is the virus receiving the most attention now, but malaria alone kills more than 400,000 people a year, and scores of thousands die from mosquito-borne yellow fever and dengue. To this day, insects smaller than a child’s thumbnail remain the most dangerous nonhuman animals on the planet.
And we are still trying to figure out how to vanquish them. There’s a line one hears frequently from entomologists and other mosquito experts, especially amid the Zika alarms: “We have no silver bullet.” What they really mean is no stake through the heart; silver bullets are for werewolves. Mosquitoes—some of them, anyway—are vampires. Of the 3,500 species that researchers have identified so far, only a few hundred feed on human blood, including the Zika-carrying Aedes aegypti and Aedes albopictus. Some, notably Ae. aegypti, turn out to be assailants of astonishing formidability.
Start with their physical equipment, especially in the mosquitoes that are the most anthropophagous, which is an elegant way of saying they prefer human blood. A mosquito homes in on you by sensing the proximity of blood from your sweat, your breath, your warmth. Her feeding apparatus, that elaborate proboscis, is a multipart marvel with a skin-piercing fascicle of tiny stylets that can suck your blood while injecting mosquito saliva laced with an anticoagulant. A mosquito can slip that fascicle into your skin so gently that you have no idea what’s happening until the blood meal is already under way. She can sip your blood until she’s more than twice her weight and has to lumber off someplace to rest, jettisoning the liquid and retaining the nutrients, before she can fly properly again.