Have you ever wondered which animal is responsible for killing the most people? Perhaps a shark?  Maybe some type of snake or spider? Or maybe some sort of large land mammal like a grizzly bear or a lion?

If you were thinking along those lines, then I’m sorry to disappoint, but the deadliest animal known today is quite a bit smaller than all of those. Believe it or not, found almost everywhere, on every continent except Antarctica, our deadliest animal is the mosquito!

Yes, that is correct! At more than 1 million fatalities each year, the mosquito is most certainly the deadliest of all animals. How is this possible? Well, mosquitos are notorious for transmitting diseases. They carry with them diseases like malaria, dengue fever, yellow fever, encephalitis, West Nile virus, and countless others. Acting as vessels for diseases, mosquitos transmit these diseases to either us, or animals. These diseases can then make us very ill and sometimes even lead to death. It is not actually one type of mosquito that is transmitting all of these diseases, but in fact, it’s several. The most common belong to the genera Aedes (Dengue and Yellow Fever), Anopholes (Malaria and Canine heartworm), and Culex (West Nile, Encephalitus and Avian Malaria).

Mosquitos need the protein in our blood, or the blood of other animals, in order to lay their eggs.  This means that only the female mosquitos need blood. In other words, next time you find yourself scratching away at one or more of those incredibly itchy and annoying mosquito bites, you can thank female mosquitos for that. The male mosquitos are content living off plant nectar.

The way a female mosquito bites us is by sticking her thin, sharp proboscis into our flesh.  As she draws blood she inserts some of her saliva along with anti-coagulates to keep the blood from clotting. This is where the danger lies and gives mosquitos the rightful title of being the most deadly.  In the mosquito saliva there could be viruses and parasites lurking, ready to infect us. These diseases can be deadly, but are not normally transmittable between humans. However, mosquitos are doing an excellent job acting as vectors for transmission of these diseases.

But how exactly do the mosquitos find us? Mosquitos have several different ways to sense living things so that they can then bite and extract blood. The first of those is chemical sensing. Mosquitos can actually detect CO2 in the air from about 100 feet away. As we and other animals around us exhale, mosquitos are alerted of our presence.

So maybe we can just hold our breath next time we see a mosquito? Well, it’s not quite that easy. Mosquitos can also detect heat and have visual sensors that can detect color contrast and movement.

It might be a little harder to trick that mosquito!

Although attempting to hide completely from mosquitos might not work, there are plenty of things we can do to make our lives a little easier and safer, such as:

  • Wear long sleeves and pants during periods of high mosquito numbers.
  • Put on mosquito repellents that contain DEET when spending time outside.
  • Avoid being outside during dawn, dusk, or late evening when mosquitos are the most active.
  • Eliminate sources of stagnant water around your home. Stagnant water attracts mosquitos and gives them a good place to lay their eggs.
  • If you have a pond in your yard, consider stocking it with fish like Gambusia, which feed off mosquito larvae.


As irritating as these insects can be, they have been around for a whole lot longer than us – about 30 million years. So, it seems inevitable that we must learn to exist with them, but it doesn’t hurt for us to have some kind of upper hand to protect ourselves.

Discover more unbelievable facts at “The Science of Ripley’s Believe It or Not!®” at Arizona Science Center through May 4, 2014!


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