H.H.
Are you talking about that nits (eggs) that attach to the hair? You remove them with a specialized comb. If you don't get them all out, you cannot break the life cycle of the lice.
I"m not sure how you treated the lice. But let me tell you that neither the over the counter, nor the prescription shampoo lice treatments work.
1. Do a 4 hour oil treatment (douse hair and scap in a oil-this kills live bugs)
2. Comb the nits out (order a Terminatior comb on line).
3. Wash all bedding and dry on high heat, same with recently worn clothing. Vacuum furniture and car seats. Bag up stuffed animals.
4. Repeat oil treatment 8-10 days after the first. This will break the life cycle if you missed any nits. A live bug is not old enough to lay eggs for 7 days. So its critical that you do not do the second oil treatment too late or too early.