We’re approaching peak mosquito season, and with it a lot of itchiness, futile swatting, and pyrrhic victories over individual mosquitoes quickly followed by panic, as a dozen of their closest friends descend upon you to seek vengeance.
You can be forgiven, given all this unpleasantness, if you’re not particularly curious about how mosquitos do what they do. But as an NPR story from yesterday reveals, the mechanics of mosquitoes’ blood-sucking are actually really, really interesting, and constitute a fairly new area of research.
The story comes with a nifty PBS mini-doc on the subject:
Part of the reason some researchers have been so keen on figuring out the secrets of mosquito blood-sucking is that those little pests are the deadliest animals in the world. As NPR’s Gabriela Quirós points out, “mosquitoes kill hundreds of thousands of people each year worldwide, and sicken millions more.” (And the Zika virus has, of course, only rendered the insects scarier lately.)
It’s taken a long time for researchers to finally gain a nuanced understanding of how mosquito bites work. As Quirós notes, “the insect’s delicate mouthparts tend to fall apart in the hands of beginners. Keen dissection skills — aided by video, powerful microscopes, and genetic analyses — are now enabling [Young-Moo Choo, a postdoctoral researcher at the University of California, Davis] and other scientists to gather the details they need to figure out how the feeding system works.” Zoomed-out, the process might seem simple: The bug lands, pierces the skin, and slurps away. In reality, it’s a lot more complicated, and while the insects might be an annoying public-health threat, they’re also a remarkable feat of evolutionary engineering.
For one thing, they’ve developed all sorts of ways to figure out exactly where our blood is, like “receptors on the tip of the labrum [that] respond to chemicals in our blood that drift up through the tissue … to help guide the way to a likely vessel.” Perhaps just as impressive are the six “needlelike parts” female mosquitoes — they’re the ones who bite — use to get at our tasty, tasty blood:
When the female mosquito pierces the skin, a flexible liplike sheath scrolls up and stays outside as the insect pushes in the six needlelike parts.
Two of these needles, called maxillae, have tiny teeth that let the mosquito saw through human skin.
Another set of needles, the mandibles, holds tissues apart while the mosquito saws into the skin. Then a fifth needle, called the labrum, pierces a blood vessel.
Perhaps most demoralizing about all this, from the human perspective, is that the blood is used by the females to grow their eggs. Yup: The blood a mosquito steals from you goes into her eggs to make more mosquitoes to steal more blood from you to make more eggs to make more mosquitoes.
Nature is terrible. Terrible but interesting.