Head Lice: 9 Weird Facts You Probably Didn’t Know

These little pests are masters of disguise.

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Despite the panic about head lice that spreads the minute you get that dreaded letter home from school, these little creatures are not at all dangerous to humans. They don’t transmit diseases and they don’t usually cause pain—just annoying itching and some simple treatment.

Still, head lice are rather mysterious parasites, and it’s easy to fear the unknown, so let’s clarify a few key things about these critters. These nine facts about head lice won’t make you love them, but you’ll probably be a little calmer next time you hear about a lice outbreak at your kid’s school or camp.

  1. The singular form is a “louse.” Let’s start simple. It might sound weird because you’ve never said it aloud, but this one follows the same rule as “mice” and “mouse.”

  2. Lice cannot fly or hop. Don’t worry about a louse leaping from someone’s head on the subway—these critters can only crawl. In fact, they have special hook-like claws that help them hang onto human hair, which is why you rarely find them anywhere else. Because they can’t fly, you can only get head lice through head-to-head contact, according to the CDC.

  3. Lice avoid the light, and they can crawl quickly to stay hidden in the dark. This is partly why they are so difficult to spot.

  4. Nits (the eggs of lice) can camouflage themselves. They contain pigment to match the hair color of the host. This protects them from threats (yep, that’s you) so you’re less likely to find them and, um, kill them.

  5. The itching is caused by their saliva, not the crawling. Similar to mosquitos, the bite of a louse causes an allergic reaction in the skin that leads to that uncomfortable itching. (That said, the crawling itself can cause a tickling feeling.)

  6. Hair length doesn’t influence your risk of getting lice. It’s a myth that having short hair will prevent lice from camping out on your scalp, and an even bigger myth that dirty hair will attract them. While girls are statistically more likely to get lice, it’s because they tend to play more intimately than boys do, not because of their longer locks. And we repeat: head lice is not a sign of poor hygiene of the person or their home.

  7. Pets do not carry head lice, so breathe a sigh of relief. (Fleas, of course, are another issue.)

  8. Lice infest an estimated 6 to 12 million Americans a year, based on sales of pediculicides. The population most commonly at risk is preschool and elementary school children.

  9. A louse can only survive off the scalp for one or two days. Lice feed off human blood, so if a louse ends up on the carpet, it will likely die there within 48 hours. For that reason, it’s unnecessary to fumigate the house if someone in your family gets lice. Wash and vacuum what you can, but lice do not require the same level of diligence as, say, bed bugs (thank goodness).

Lice are nothing to fear, but that doesn’t mean you should have to deal with them. Here are must-know tips for preventing head lice.