The loathsome, lethal mosquito - Rose Eveleth

View full lesson: http://ed.ted.com/lessons/the-loathsome-lethal-mosquito-rose-eveleth

Everyone hates mosquitoes. Besides the annoying buzzing and biting, mosquito-borne diseases like malaria kill over a million people each year (plus horses, dogs and cats). And over the past 100 million years, they've gotten good at their job -- sucking up to three times their weight in blood, totally undetected. So shouldn't we just get rid of them? Rose Eveleth shares why scientists aren't sure.

Lesson by Rose Eveleth, animation by Karrot Animation.

What's the worst bug on the planet?

You might vote for the horsefly
or perhaps the wasp,

but for many people,

the worst offender is by far the mosquito.

The buzzing, the biting,

the itching,

the mosquito is one of the most commonly
detested pests in the world.

In Alaska, swarms
of mosquitos can get so thick

that they actually asphyxiate caribou.

And mosquito-borne diseases
kill millions of people every year.

The scourge
that is the mosquito isn't new.

Mosquitoes have been around
for over a hundred million years

and over that time have coevolved
with all sorts of species,

including our own.

There are actually thousands
of species of mosquitos in the world,

but they all share one insidious quality:

they suck blood,

and they're really, really
good at sucking blood.

Here's how they do it.

After landing, a mosquito will slather

some saliva onto the victim's skin,
which works like an antiseptic,

numbing the spot so we don't
notice their attack.

This is what causes the itchy,
red bumps, by the way.

Then the bug will use
its serrated mandibles

to carve a little hole in your skin,

allowing it to probe around
with its proboscis,

searching for a blood vessel.

When it hits one,
the lucky parasite can suck

two to three times its weight in blood.

Turns out we don't really
like that too much.

In fact, humans hate mosquitos so much

that we spend billions
of dollars worldwide

to keep them away from us --

from citronella candles

to bug sprays to heavy-duty
agricultural pesticides.

But it's not just
that mosquitos are annoying,

they're also deadly.

Mosquitos can transmit everything
from malaria to yellow fever

to West Nile virus to dengue.

Over a million people worldwide

die every year
from mosquito-borne diseases,

and that's just people.

Horses, dogs, cats,

they can all get diseases
from mosquitoes too.

So, if these bugs are so dastardly,
why don't we just get rid of them?

We are humans after all,

and we're pretty good
at getting rid of species.

Well, it's not quite so simple.

Getting rid of the mosquito
removes a food source

for lots of organisms,
like frogs and fish and birds.

Without them,
plants would lose a pollinator.

But some scientists say

that mosquitos aren't
actually all that important.

If we got rid of them, they argue,

another species would simply
take their place

and we'd probably have far
fewer deaths from malaria.

The problem is that nobody
knows what would happen

if we killed off all the mosquitos.

Something better might take their spot

or perhaps something even worse.

The question is,
are we willing to take that risk?

(Buzzing)