Curious Kids: what's the point of nits?!

Curious Kids is a series for children. If you have a question you’d like an expert to answer, send it to curiouskids@theconversation.edu.au You might also like the podcast Imagine This, a co-production between ABC KIDS listen and The Conversation, based on Curious Kids.

What’s the point of nits?! – Connie, age 9, Nambour, Queensland.

Great question, Connie. I often find myself scratching my head trying to figure out the answer to that question too!

What we commonly call “nits” are actually the eggs of very small insects known as head lice. And head lice are found nowhere else on the planet except in human hair.

Head lice have adapted perfectly to life on us. They have specially designed claws at the ends of each of their six legs that are perfect for scuttling up and down the shafts of hair.

In fact, they’re so perfectly designed for life on our hair that once they come off they’re incredibly clumsy and have a tough time getting around at all. That’s why they’re most commonly spread between children through direct head-to-head contact. Lice are tricky enough to navigate the tangle of two people’s hair.

Once lice have infested someone, they will climb down the hair to the scalp and bite. They need our blood to live and lay eggs. While we’ll sometimes get a reaction to their bites, that reaction is rarely as bad as they type we get from mosquitoes or ticks. Importantly, head lice don’t transmit the germs that make us sick like those other pests. At worst, we’ll just get a little itchy.

Read more: Curious Kids: When we get bitten by a mosquito, why does it itch so much?

So, what is the point of head lice? Perhaps they don’t have a “point” at all. We like to think that all creatures play a role in the local ecosystem. We’re especially interested in insects that provide a benefit for people too. A great example are the bees and other insects that pollinate our crops that are crucial in providing food.

But perhaps head lice don’t play what we would traditionally see as an important role in the ecosystem. They don’t pollinate plants, they’re not food for other animals, and they don’t exactly bring joy to our lives in the way other, cuter animals do. When it comes to charismatic insects, head lice aren’t quite up there with butterflies or dragonflies!

I think lice see us as playing a role – providing them with food – but the reverse may not be true.

Read more: Curious Kids: why do we have two kidneys when we can live with only one?

Perhaps we need to take a different perspective when thinking about the “point” of head lice. We marvel at the ability of plants and animals around the world to adapt to all the weird and wonderful cracks and crevices in the environment. Why shouldn’t we take inspiration from head lice being able to adapt to life on the human body?

Like many of the other insect pests that impact our lives, it can be hard to be sympathetic to head lice. As concern is growing about global insect declines, I’m sure parents and carers trying to wrangle lice-infested children aren’t thinking about insect conservation!

Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to curiouskids@theconversation.edu.au

Please tell us your name, age and which city you live in. We won’t be able to answer every question but we will do our best.

Cameron Webb and the Department of Medical Entomology, NSW Health Pathology and University of Sydney, have been engaged by a wide range of insect repellent and insecticide manufacturers to provide testing of products and provide expert advice on the biology of medically important insects. Cameron has also received funding from local, state and federal agencies to undertake research into mosquito-borne disease surveillance and management as well as risk assessment of a wide range of arthropod pests of public health importance.