Lice start out as eggs or nits that attach to the hair shaft of humans. Lice eggs are oval shaped and range from yellow to white coloring. They are only about the size of a knot in a string and are usually found about ¼ inch down from the scalp. Because the eggs remain in a shell for protection, many lice products have trouble penetrating through and killing the lice. A lice shampoo can be applied later, once the eggs hatch, in order to effectively kill the new lice or a lice egg comb can be used to remove lice eggs before they hatch.