Acts on the nerve cell membrane to disrupt the sodium channel current by which the polarization of the membrane is regulated. Delayed repolarization and paralysis of the pests is the outcome. Treatment of infestation with head lice ( Pediculus humanus capitis ) and its nits (eggs). A-Scabs, a pyrethroid, is active against a broad range of pests including lice, ticks, fleas, mites, and other arthropods. Topical/Cutaneous Head pediculosis Directions Apply lotion thoroughly to all body parts from the head to the soles of the feet and leave the medication on for 8 - 14 hour, then wash off completely.