kill'er good and dead."

Citronella,

netting,

DEET.

All the things we use to arm ourselves

against a pesky foe,

the mosquito.

There are over 3,000 species

of these arthropods in the world.

If you're in North America,

you can be bitten by 175 different types.

These blood-sucking pests carry diseases

such as malaria and the West Nile virus,

and they cause an average of 2 million

deaths around the world each year.

Our attempt at curbing the population

of mosquitoes has, so far, failed.

One of the reasons this disease-carrying bug

is so dangerous is because of its size.

We usually don't know when a

mosquito is biting us,

and even if we do, it's too late.

Like vampires, mosquitoes are known for blood-sucking.

But they don't do it for nourishment.

Like many other bugs,

mosquitoes need sugar from nectar to survive.

So why do they suck animal blood?

Female mosquitoes need a particular protein

and lipid only found in animal blood

in order for them to lay eggs.

A standard mosquito weighs just 2.5 mg,

but they need a sizeable 1 mg of blood

just to produce 40 eggs.

And, they can lay up to 300 eggs

during their average lifespan of 2 to 6 weeks.

This is why only female mosquitoes bite and draw blood.

So what would happen if they were the size of humans?

For starters, transmitting diseases would be the last thing you'd worry about.

If a female mosquito were 79 kg (175 lbs)

and still required almost three times her

body weight in blood over her life cycle,

then she would need 237 kg (525 lbs) of animal blood

to lay those 300 eggs.

In other words,

she would need to suck every last drop of blood from your body.

And from 236 other people, too.

Yikes.

At the very least,

it could become difficult for female mosquitoes

to get enough blood to lay her maximum amount of eggs,

so the population might begin to decrease quickly.

And we'd probably want to kill as many as possible.

Maybe scientists would develop some sort

of pesticide that only harmed mosquitoes and not humans.

Or maybe they'd become another

big game target to hunt down.

It's also possible that predators

would begin to eat mosquito eggs and larvae,

further curbing the population.

A mosquito has an exoskeleton,

meaning it has to molt as it grows.

This period of transition would be a vulnerable

time and could make killing them much easier.

Human-sized mosquitoes would be bad news,

and not just because they could easily kill us.

They would likely target cattle, horses,

and large wild mammals,

creating chaos in both the meat industry and nature.

But would a mosquito even be able to survive at 79 kg (175 lbs) in our current atmosphere?

Probably not.

Arthropods breathe through openings

called spiracles that connect to a

branching network of trachea.

This network of tubes diffuses

oxygen throughout their body.

Because of this system,

the amount of oxygen in the air limits their growth.

At that time, arthropods were huge!

But today, the oxygen in our atmosphere is only 21%.

That's not enough for a human-sized mosquito.

Even if it was,

mosquitoes would need to develop a much

stronger exoskeleton to support all that extra weight.

And because they'd need more

nectar to sustain themselves,

many would likely starve.

We might not see human-sized mosquitoes any time soon,

but we could see a rise in giant mosquitoes called 'Gallinippers'.

These mosquitoes are 20 times larger

than their cousins and are native to North America.

They are so large, they are able to bite through clothing!

Since mosquitoes are cold-blooded,

they need temperatures over 26 °C (78.8 °F).

With global temperatures on the rise,

Gallinippers could easily expand their range and population.

Another possibility is that the growth of mosquitoes

could also spur the growth of their natural predators.

Just imagine giant spiders roaming the Earth.

But that's a story for another What If.