I am a lurker on this list but this subject is making me answer. A few years ago we had a problem with lice. My granddaughter was always coming home with them.
She had waist length hair. A friend of mine in New Zealand told me to buy a shampoo with Tea Tree oil in it. Than to get a bottle of Tree Tea oil and add about 15 or 20 drops it to the shampoo.
(Walmart carries Tea Tree oil) We tried it and it will never use anything else. It not only kills the lice it gets rid of the nits. You just wash the hair and leave it on for about 10 to 15 minutes. Sue from SD