What insect is
responsible for more human deaths each year than any other
We got a couple of half-right answers to this one. We'll post those folk's names as soon as we get their okay. It was the "how do they do it" part that got most of you.
Some guessed that bees were the most deadly insect, no doubt the result of the "killer bee" hype. While a few people have died from "killer bees" (more accurately called Africanized Honey Bees), they are more of a threat to cattle, other animals, or infants or otherwise defenseless people. Very few people have ever died from the infamous "killer bees" - they just have a scary popular name and so get a lot of bad press.
Other folks thought that scorpions were the top human killers. Again only a very few people each year die from scorpion stings. Most are just as dangerous as bees stings. While some scorpions are actually deadly to humans, we don't come in contact with many of those species. The same holds for spiders and tarantulas. Some could kill people, but few ever do. Even the much feared Black Widow spider rarely kills people, it just hurts a lot.
Mosquitoes are the #1 killer of humans in the world (sort of)! About 2 million people die each year from a disease resulting from a mosquito bite. The disease is called Malaria, and is caused by a small animal, called a Plasmodium that gets into people through a mosquito bite.
Only female mosquitoes bite. They use protein from blood to make the shells of their eggs. (Male and female mosquitoes eat nectar from flowers - like butterflies and hummingbirds... nice, huh?!) The female mosquitoes have a problem, though, when they try to suck our blood. When our blood gets outside of our body, the cells tend to stick together. We know this as clotting and it's why you get a scab when you cut yourself - its scientific name is "coagulation". Coagulation is a big problem for a mosquito who has a very thin tube through which to suck blood. The stuck together blood cells clog her tube and she cannot get good blood through it.
To combat coagulation, the mosquito first spits into us when she bites!! She spits a chemical called an "anti-coagulant" that keeps the blood cells from sticking together so she can suck as much as she wants! It is during the spitting phase of biting that the Malarial Plasmodium gets into you.
Once inside a mammal, the Plasmodium goes through the bloodstream and into the liver where it reproduces. From the liver, the Plasmodium cells get into red blood cells and begin to feed. Inside the red blood cells, the Plasmodium cells divide and eventually split the red blood cells open and a bunch of new Plasmodium cells infect other red blood cells. The cycle continues as the host animal gets sicker and sicker and often dies.
Fortunately, the type of Plasmodium that causes Malaria and the species of mosquito (in the genus Anopheles "an-off-eh-lees") that spreads it do not live in the United States, but in many other countries (especially in tropical regions), this is a very dangerous disease. Therefore, a lot of research money is available for the study of Malaria and mosquitoes (which also spread other diseases in much the same fashion).
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