Here's What Happens Inside You When A Mosquito Bites

“I was genuinely amazed to see the footage,” says James Logan from the London School of Hygiene and Tropical Medicine, who studies mosquitoes. “I had read that the mouthparts were mobile within the skin, but actually seeing it in real time was superb. What you assume to be a rigid structure, because it has to get into the skin like a needle, is actually flexible and fully controllable. The wonders of the insect body never cease to amaze me!”

From afar, a mosquito’s snout might look like a single tube, but it’s actually a complicated set of tools, encased in a sheath called the labium. You can’t see the labrum at all in the videos; it buckles when the insect bites, allowing the six mouthparts within to slide into the mouse’s skin.

Four of these—a pair of mandibles and a pair of maxillae—are thin filaments that help to pierce the skin. You can see them flaring out to the side in the video. The maxillae end in toothed blades, which grip flesh as they plunge into the host. The mosquito can then push against these to drive the other mouthparts deeper.

The large central needle in the video is actually two parallel tubes—the hypopharynx, which sends saliva down, and the labrum, which pumps blood back up. When a mosquito finds a host, these mouthparts probe around for a blood vessel. They often take several attempts, and a couple of minutes, to find one. And unexpectedly, around half of the ones that Choumet tested failed to do so. While they could all bite, it seemed that many suck at sucking.

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The video below shows what happens when a mosquito finally finds and pierces a blood vessel. On average, they drink for around 4 minutes and at higher magnifications, Choumet could actually see red blood cells rushing up their mouthparts. They suck so hard that the blood vessels start to collapse. Some of them rupture, spilling blood into the surrounding spaces. When that happens, the mosquito sometimes goes in for seconds, drinking directly from the blood pool that it had created.