This is the deadliest animal in the world. Mosquitoes kill hundreds of thousands of people
each year… the most vulnerable people: children, pregnant women… No other bite kills more humans… or makes
more of us sick. So what makes a mosquito’s bite so effective? For starters, they’re motivated. Only females bite us. They need blood to make
eggs… And a pool of water for their babies to hatch in. Even a piece of trash can hold enough. At first glance, it looks simple — this mosquito
digging her proboscis into us. But the tools she’s using here are sophisticated. First, a protective sheath retracts – see
it bending back? If you look at a mosquito’s head under a
microscope, you can see what that sheath protects. And inside *there* are six needles! Two of them have tiny teeth. She uses those to saw through the skin. They’re so sharp you can barely feel her pushing. These other two needles hold the tissues apart while she works. From under the skin, you can see her probing, looking for a blood vessel. Receptors on the tip of one of her other needles pick up on chemicals that our blood vessels exude naturally and guide her to it. Then she uses this same needle like a straw. As her gut fills up, she separates water from the blood and squeezes it out. See that drop? That frees up space to stuff herself with
more nutritious red blood cells. With another needle, she spits chemicals into us. They get our blood flowing more easily, and give us itchy welts afterwards. And sometimes, before she pries herself away, she leaves a parting gift in her saliva: a virus or a parasite that can sicken or kill
us. There’s nothing in it for her. The viruses
and parasites are just hitching a ride. But this is what makes mortal enemies out of us
and mosquitoes. They take our blood. Sometimes we take theirs.
But often, not soon enough. Good. You’re still there. . These are the
larvae of Culex pipiens, a.k.a. the common house mosquito here in California. Gross, right?
Well, you can avoid them by emptying your rain gutters. Pet water dishes too. While
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