New alternative insecticides are necessary for the chemical control of head lice. In this study the fumigant knockdown time 50% (KT50
) and repellency index (RI) of three aliphatic lactones was compared with two essential oils and DDVP, against permethrin-resistance Pediculus humanus capitis
s from Argentina. In the fumigant assay, none of the lactones were effective compared to the highest activity of eucalyptus (KT50
15.53 m). In the repellency test, the three lactones were equally or more effective (RI ranging from 60.50 to 76.68) than the positive control (piperonal). These lactones are promising as head lice repellents.