If you let your kids use those headphones at media centers or music stores, it is the same as sharing a comb with all the people who have used it before. Lice can climb into their hair this way.
Also, here are tons of natural and nontoxic, tried and true tips on lice treatment and prevention. Some of these I have never heard of. Here is the link:
http://www.earthclinic.com/cures/lice.html
There are a lot of good ideas here on lice prevention.
By Robyn Fed from Hampton TN
It requires a lot of work to get rid of head lice, so prevention is vital. This page explores the idea of using hairspray for lice prevention.