Humanity's itchy little nuisance resists common pesticides and drives parents crazy. Will we ever be rid of head lice? Doctors say it's unlikely. Nothing may inspire more panic than getting that ...

The human-head louse has a ghostly quality. It tends to glimmer in and out of view, leaving only subtle signs and omens of its presence. Is that oblong speck an egg sac or a flake of dandruff? Was ...