You do NOT have to use a pesticide on your children's head to get rid of head lice.
Please go to headlice.org and read up on it.
I wash the kiddo's hair in the shower with regular shampoo and then use a great conditioner. I comb the tangles out of their hair with the conditioner in it. You can often find lice in the conditioner that gets combed out. That's one less you have to worry about.
Then I leave their hair drippy wet. I get a white or light towel over my lap and I get their hair up in sections about an inch each one. Lice can't handle the water well and it makes them groggy. They are sluggish and can't move hardly at all.
I use a small tooth rat tail comb and go through each one inch section. I look for bugs all the way from the scalp to the end of the hair. As I find groggy bugs I pull them off and put them into a cup of water, they're like us and breathe air so they drown if they can't get out of the water, problem solved. As the hair starts to dry you need to get it drippy wet again.
When you go through her whole head you'll also see nits. If it's solid white it's empty and of no consequence. If it has a black center it has a baby in it and it must come out. Pull gently but constantly down the hair shaft until it slides off the end. That egg also needs to go into that cup of water.
Once you go through her hair that way you need to do it again the next day and the next day and the next...until there are no new bugs and you don't see any new nits then you can go to doing this weekly.
If a child is in school they will get lice. If a child goes to child care they will get lice. Lice are everywhere. They are on the fabric chairs in doctors offices, they are in the seats of the neighbors van when they take your child to school or to an activity, they are in the hats at the store that kids grab and try on, etc....it's better to be aware of where they like to live and where they can crawl onto your child's head.
So go to the site and learn all about head lice and how to prevent and manage them better.
One thing you can do is go to Walmart and buy a small, 8 ounces or less, spray bottle and put some Tea Tree Oil in it then add some water. The water isn't pure, the air in the bottle isn't pure, the bottle isn't sterile. SO if you leave the fluid in the bottle more than a few days it will sour. So the less you make up the less you have to throw out in a few days.
Spritz the child's hair each morning before you brush out their tangles and style their hair. The Tea Tree Oil stinks to lice. They will not like the host and will crawl off. Using products with Tea Tree Oil in them will also help repel the lice.