How Lice Turn Your Hair Into Their Jungle Gym | Deep Look

Why are itchy lice so tough to get rid of and how do they spread like wildfire? They have huge claws that hook on hair perfectly, as they crawl quickly from head to head.

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Head lice can only move by crawling on hair. They glue their eggs to individual strands, nice and close to the scalp, where the heat helps them hatch. They feed on blood several times a day. And even though head lice can spread by laying their eggs in sports helmets and baseball caps, the main way they get around is by simply crawling from one head to another using scythe-shaped claws.

These claws, which are big relative to a louse’s body, work in unison with a small spiky thumb-like part called a spine. With the claw and spine at the end of each of its six legs, a louse grasps a hair strand to hold on, or quickly crawl from hair to hair like a speedy acrobat.

Their drive to stay on a human head is strong because once they’re off and lose access to their blood meals, they starve and die within 15 to 24 hours.

--- How do you kill lice?
Researchers found in 2016 that lice in the U.S. have become resistant to over-the-counter insecticide shampoos, which contain natural insecticides called pyrethrins, and their synthetic version, known as pyrethroids.

Other products do still work against lice, though. Prescription treatments that contain the insecticides ivermectin and spinosad are effective, said entomologist John Clark, of the University of Massachusetts, Amherst. They’re prescribed to kill both lice and their eggs. Clark said treatments such as suffocants, which block the lice’s breathing holes, and hot-air devices that dry them up, also work. He added that tea tree oil works both as a repellent and a “pretty good” insecticide. Combing lice and eggs out with a special metal comb is also a recommended treatment.

--- How long do lice survive?
It takes six to nine days for their eggs to hatch and about as long for the young lice to grow up and start laying their own eggs. Adult lice can live on a person’s head for up to 30 days, according to the Centers for Disease Control and Prevention (CDC).

--- Can your pet give you lice?
No. Human head lice only live on our heads. They can’t really move to other parts of our body or onto pets.

---+ Read the entire article on KQED Science:
https://www.kqed.org/science/1939435/how-lice-turn-your-hair-into-their-jungle-gym

---+ For more information:
Visit the CDC’s page on head lice: https://www.cdc.gov/parasites/lice/head/index.html

---+ More Great Deep Look episodes:

How Mosquitoes Use Six Needles to Suck Your Blood:
https://www.youtube.com/watch?v=rD8SmacBUcU

How Ticks Dig In With a Mouth Full of Hooks:
https://www.youtube.com/watch?v=_IoOJu2_FKE

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