Since it has been six months, these eggs (nits) are empty casings and no longer active. Permethrin kills lice but does not dissolve the strong glue holding the casings to your hair. To remove them, apply ordinary white vinegar to your hair, leave it on for 15 to 20 minutes, and then comb through thoroughly with a fine-toothed metal nit comb. The acetic acid in vinegar helps break down the sticky glue. Alternatively, you can buy over-the-counter nit-loosening rinses or dimethicone-based products designed to lubricate the hair shaft for easier combing. Diligent combing is the most effective way to clear them completely.