I read this with a healthy amount of skepticism because it seems a little like a snake oil proposition. As it turns out, snake oil could kill the lice as well because any oil or product with a lot of oil (like mayonnaise) serves to suffocate the little monsters. The Minnesota Department of Health lists mayonnaise as an acceptable suffocant for treating head lice. Oil and petroleum jelly are listed as well. A think coating is necessary, and because you're not actually poisoning the lice you have a higher margin of error. That said, suffocating them with an oily product can and has worked for many people. It's worth a try if you're particularly adverse to using harsh chemicals.
Lice in America carry genes that may make them resistant to the most commonly used over-the-counter treatments. The study presented at the National Meeting & Exposition of the American Chemical Society reports that the overuse of treatments may have led the tiny bugs to evolve and develop a trio of mutations that are resistant to the insecticides used in lice shampoos. For the study, Dr. Kyong Yoon, an assistant professor in the Biological Sciences and Environmental Sciences Program at Southern Illinois University, collected 109 samples from 30 states and found all three genetic mutations in samples from 25 states, including California. One or two mutations were present in samples from four states; Michigan was the only state without any mutations. Anywhere from 6 to 12 million U.S. kids, mainly between the ages of 3 and 12, have head lice annually.