Deep Look

Watch out you might not always see these five tiny creatures coming for you, but chances are youve got one lurking nearby ready to suck your blood.

We show you how they do it and how you can get rid of them.

Enjoy!

This is the deadliest animal in the world.

Mosquitoes kill hundreds of thousands ofpeople 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 mosquitos bite so effective?

For starters, theyre motivated.

Only females bite us.

They need blood to make eggs ... anda 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 shes using here are sophisticated.

First, a protective sheath retracts see it bending back?

If you look at a mosquitos head under amicroscope, 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.

Theyreso 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 otherneedles 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 fromthe 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 chemicalsinto us.

They get our blood flowing moreeasily and give us itchy welts afterwards.

And sometimes, before she pries herself away, she leaves a parting gift in her saliva, avirus or a parasite that can sicken or kill us.

Theres 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 taketheirs.

But often, not soon enough.

On to our next miniature vampire.

Lets see how ticks dig into you with a mouthfull of hooks, and the best way to pry them loose.

The hills are alive ... with silent, waiting ticks.

Their bites can transmit bacteria that causeLyme disease, and other thingsthat can make us very sick.

Protected by these palps is a menacing mouth ... ... covered in hooks.

First she has to find a host.

She can sense animals like us by the carbon dioxide we give off.

She reaches out with her front legs.

Scientists call this questing.

It willuse that claw to latch onto something likeyour sleeve.

Now you see her ... ... now you dont.

Once aboard, she searches out a nice spot to bite into for blood.

She lives three years, but in that time she only eats three meals.

A tick needs enough blood to grow from larva to nymph, nymph to adult, and then for females to lay their eggs.

Gross.

Lets check out a nymph, a young tick.

Its tiny, smaller than a freckle.

To grow into an adult, it needs one blood meal, a big one.

The front of its body is all mouth.

It digs into us using two sets of hooks.

The hooks wriggle into the skin.

They pull our flesh out of the way andpush in this mouthpart: the hypostome.

Those hooks anchor the tick to us for the long haul, like mini-harpoons.

While the speedy mosquito digs in, sucks our blood and splits, all within seconds, a tick nymph stays on for days.

Three days, if we dont find it before then.

Compounds in their saliva help blood pool under the surface of our skin.

The nymph sips it through its mouthparts, like drinking from a straw.

When a tick is full and I meancompletely full it falls off whereverit may be.

Maybe onto your bed.

Thats if you dont nab it first.

You might have heard that you should twist orburn the tick.

Not true.

Grab the tick close to your skin and just pull straight out.

Thats howyou win the fight against those tenacious hooks.

If that didn't make your skin crawl, this will definitely make your scalpitch.

Its time to find out how lice turn your hair into their personal jungle gym.

It can start as an itch.

Maybe a tickle on your scalp.

Its head lice.

Tiny and tenacious.

Thanks to millions of years of evolution, these suckers are not easy to get rid of.

You might end up in a salon, but not the kind for haircuts.

Young lice are so small theyre almost impossible to see with the naked eye.

Our scalp is their buffet.

They feed on our blood.

You can see it inside this adultlouse.

Its that brownish stuff thats moving.

The secret to their success?

Their claws called tarsal claws and this little part, called a spine.

A pair on each of its six legs.

Theyve evolved to fit perfectly around a human hair.

They make lice into speedy little acrobats, using our hair like a tightrope.

They cant jump or fly, but they get around.

Say two kids one blond, one brunette touch heads.

The louse just scoots right over.

Its been one long game of hopscotch, from human head to human head.

And it has to be us.

Our head lice cant live on other animals.

In fact, other primates have their own species of lice, adapted to their unique hair.

Birds have lice that hide intheir feathers.

Ooh.

Cozy.

And we all want them gone.

Common insecticides wont kill our head lice anymore.

Theyve become resistant to them.

Even their eggs have serious staying power, glued to individual strands of hair.

But lice do have a weakness.

They cant survive away from our moist, warm scalp.

Head licecannot even live on other hairy parts of our body.

So if you or a professional painstakingly combthem out, theyll starve, and die within hours.

Okay, its not fun.

But its just a temporaryencounter with a tiny hitchhiker thatis biologically destined just for you.

These beauties are kissing bugs, but you wouldnt want to kiss one becausepretty quickly they swell into a balloon full of your blood.

This kissing bug isnt going to give you a lovingpeck when it sticks you with that tucked-away proboscis.

It could actually make you really sick, even kill you.

It makes its move at night, while youre sleeping.

It likes your warm body.

Kissing bugs get their name because they often bite near the lips or eyes, but theyll dig in anywhere youve left uncovered.

A little anesthetic guarantees you won't wake up while they feed on you for 10, 20, even 30 minutes.

Every kissing bug needs several huge meals during the year or two it lives.

As it gulps, its exoskeleton stretches like a balloon, to fit up to 12 times its weight in blood.

This pliability is called plasticization.

How it started.

How its going.

All that hot liquid could stress an insects body and stunt its growth.

So the kissing bug cools it down inside its head.

Your warm blood flows in.

The cool insect blood, called hemolymph, absorbs the heat and releases it through the top of the bugs long head.

In this infrared video, you can see the blood cool down by more than 10 degrees Fahrenheit before it reaches the bugs abdomen.

So the bug is safe.

You, on the other hand, are not.

It injects saliva as it sucks your blood.

Heres a scientist squeezing someout.

The saliva has proteins that can give people a deadly allergicreaction called anaphylaxis.

And it gets much, much worse.

Okay.

This is super gross.

After eating sometimes whileits eating ... the bug poops.

And that poop and urine ... might containthe parasite that causes Chagas disease.

If the bugs victim rubs these feces and urine into the bite wound or their eyes, the parasite can infect them.

Years later, as many as one third of the people who got the parasite develop heartdisease that can kill them, sometimes suddenly.

Pregnant women can even pass the parasite onto their babies.

Few contract the parasite in the U.S., even though kissing bugs live here.

But in Latin America, millions of people have become infected.

There, kissing bugs are known by manydifferent names: chinche besucona chinche pito vinchuca barbeiro.

In rural areas, these kissing bug species live in peoples homes, in the cracks of the walls.

And in animal coops.

Spraying has helped bring down infections.

But hundreds of thousands of people have left their home countries for the U.S., not knowing the bug gave them the parasite.

A simple blood test can find it and medications can often kill it.

In the American Southwest, the bugs live in the nests of wild animals, like thispack rat den in Arizona, where biologists Anita and Chuck Kristensen collect them.

Chuck Kristensen: Kissing bug, kissing bug!

Chuck Kristensen: Genuine kissing bug.

For the most part, they feed on the pack rats.

But in late spring and summer, the bugs sometimes travel from these nests into someones home.

So sealing off your house, with screens on your windows andeven vents , is one way to keep out these stealthy bloodsuckers.

When they feed on your blood, tsetse flies can spread disease.

But their motherly instincts are surprisingly familiar to us.

We mammals like to think were prettyspecial, right?

We dont lay eggs.

Wefeed our babies milk.

Well, this verypregnant fly is about to prove us wrong.

Yep, this tsetse fly is in labor.

Andthat emerging bundle of joy is her larva.

While other insects can lay hundreds of eggs, she grows one baby at a time inside her, just like us.

Congratulations!

Scientists think tsetse flies started growing their young like this long ago to guard them from parasites.

For that same reason, the larva doesnt stickaround.

It burrows into the dirt for protection.

Its already gotten all the nutrition it needs from its moms milk.

Thatsright, this fly makes milk.

Heres a drop of it underthe microscope.

Its madeup of protein and fat, a lot like breast milk.

The fly doesnt exactly breastfeed, though.

Inside its mom, the larva got milk through thesetubes ... which it drank with this pair of strawlike mouthparts on its head.

A female tsetse fly needs a lot of fuel, because over her 10-day pregnancy she produces her own body weight in milk.

And that fuel comes from us.

Tsetses feedexclusively on blood ... fromhumans and other animals.

Thats bad news because where the flies live in Africa they spread a debilitating disease called sleeping sickness in humans and nagana in livestock.

Tsetses make cattle so sick that they cant be raised efficiently in a region of Africa the size of the United States.

Geoff Attardo: All right.

Coming back to the first trap we set.

Narrator: People are trying to control them with things like baited traps.

Geoff Attardo: It looks like it has a lot of tsetse flies.

Geoff Attardo: Holy cow!

Thats a lot of flies.

Man: Tsetse flies.

Narrator: Theyre effective, but more defenses are needed.

Thats where Geoff Attardo, at the University of California, Davis,hopes to help.

Hes trying to stop tsetseflies from making babies in the first place.

A female only mates once in her life, enough to make the 10 or so babies shell have.

The male makes sure she doesnt mate again by delivering a substance that makes her lose interest in sex.

Scientists are trying to figure out what it is.

If they could bottle it and spray it, female tsetse flies may never get busy at all.

No more tsetse offspring to worry about.

After spending about a month below ground in a hard shell, the fly emerges as an adult and unfurls its wings.

Like us, tsetse flies ensure the next generation by investing a lot in a fewoffspring, instead of investingvery little in a lot of them.

They grow up so fast, dont they?