1-(4-chlorophenyl)-3-(2,6-dichlorobenzoyl)-urea, PH 60-38 and 1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)-urea, PH 60-40, are representatives of a new class of insecticides with an unprecedented mode of action. Susceptibility of insect species of different orders is demonstrated and the compounds are expected to be quite safe towards mammals. The compounds are stomach poisons and they are not plant systemic. Their insecticidal activity demonstrates itself mainly as a failure to moult or pupate, resulting in death. Histological examination revealed the cause of this failure to be a defect in the process of cuticle deposition.

No abstract