This is the most common way to get head lice - Nazzy Pakpour

The six-legged creature creeps down the canopy,

extends its slender trunk, and pierces the ground.

Up comes blood.

This is no regular forest.

Living where the scalp meets the hair,

these nightmarish figures are, in fact, sesame seed-sized insects,

otherwise known as head lice.

The earliest archaeological evidence of humans’ close-knit relationship with lice

is a fully preserved egg,

discovered in the hair of a 10,000-year-old Brazilian mummy.

And it seems that for as long as we’ve had lice,

we’ve fought hard to get rid of them.

Nit combs, the fine-tooth brushes used to remove lice

and their sticky eggs

have been found among the ancient remains of cultures across the globe.

This battle continues today,

as it's estimated we spend billions of dollars each year treating infestations.

So, why are lice so difficult to get rid of?

There are at are at least several thousand louse species,

as nearly all mammals deal with these parasites.

Humans are pestered by three different types,

each specialized to roam its own unique bodily terrain.

Pediculus humanus capitis live exclusively on heads

and are equipped with hook-like claws that are perfectly fitted to human scalp hair.

Pediculus humanus humanus, or body lice,

spend most of their lives embedded in clothing and bedding,

and crawling onto any nearby body part for their feedings.

In order to thrive in these changing environments,

body lice are more resilient to fluctuations in temperatures and humidity.

Meanwhile, pubic lice, also known as crab lice,

are an entirely different species.

While they also live on hair,

their claws are larger than head lice,

as they’re fitted to grasp onto the thicker cuticles found in pubic areas.

Among these three varieties, head lice are the most common.

In the US alone, it’s estimated 6 to 12 million children

deal with infestation each year.

Contrary to popular fears about catching lice from hats or hairbrushes,

most cases spread through direct head-to-head contact.

You see, head lice can only survive about 24 hours without a host to feed on.

They’re wingless and they can’t jump,

so the only way they can infest a new head is to crawl.

They can detect a new host by using their antenna to home in on body heat

and other chemical compounds that naturally emanate from the scalp.

Once they arrive on a new head, they're ready to eat.

A louse pierces the scalp with a retractable tube-like mouth

and releases a special saliva

that contains factors that open up blood vessels and help prevent clotting.

This chemical cocktail is also what makes the scalp feel itchy.

Symbiotic bacteria living in louse’s gut complement this blood meal,

by providing the additional vitamins and minerals that the louse needs to survive.

The scalp is also where lice mate.

Once mated, female lice can lay up to 8 eggs, called nits, per day.

She deposits each egg on the hair,

just a few millimeters above the scalp, and coats it with a sticky nit sheath,

which provides hydration and other factors the egg needs to survive.

This sheath hardens,

tightly cementing the nit to the hair until it hatches 8 to 9 days later.

You can’t get rid of a lice infestation

without taking care of this sticky egg problem.

While insecticide shampoos kill hatched lice,

they’re ineffective against eggs.

And nit sheaths are strong, waterproof, and resistant to chemical breakdown.

Scientists hope to bring some new tools to this old battle

by identifying treatments that can dismantle individual components

in the nit sheath,

like those that hydrate the egg and keep it alive.

But until then, there’s only one tool that’s been shown

to effectively remove eggs,

and it’s the same one that was used by ancient cultures:

a fine-toothed nit comb.

Lice are certainly stubborn survivors,

but perhaps one day, with the help of science,

these ancient parasites will haunt our nightmares— and scalps— no more.