Percent survivorship to adulthood of hatched human head louse eggs treated with ddH2O, Nix, or NYDA with and without fragrances for various exposure durations. An asterisk (*) indicates that the percent survivorship was significantly decreased compared with the ddH2O treatment after Nix, NYDA, or NYDA without fragrances treatments (ANOVA, P < 0.05). N/A = data not available because of the 100% ovicidal action of NYDA and NYDA without fragrances after the 1 and 8 h exposures.