Abstract
German cockroach, Blattella germanica (L.), nymphs in five different age Classes were treated topically with the juvenile hormone analogs fenoxycarb and hydroprene. Nymphal mortality was highest (76-100%) with 100 and 10 µg/µl concentrations of fenoxycarb applied during stages one through four. Only hydroprene applied at 100 µg/µl on first-stage nymphs was toxic. LD50’s of fenoxycarb for first and fourth stages were 197.26 and 298.82 µg/g body weight, respectively. Nymphs killed by fenoxycarb during stages one through four usually died during the period in which control nymphs molted into the next stage. Nymphal mortality caused by fenoxycarb appeared to be the result of ecdysis inhibition. Development of fifth-stage nymphs surviving the 100 and 10 µg/µl dosages of fenoxycarb was 1-9 wk longer than the controls.