Dichloro-diphenyl-trichloroethane (DDT) is one of the most widely used insecticide. Which of the following statement is NOT true about DDT?

Dichloro-diphenyl-trichloroethane (DDT) is primarily a contact poison. It acts on nervous system of insects. It permeates into the insect body through the cuticle, after dissolving in the waxy covering of the feet, and causes of paralysis of legs and wings, convulsions and finally death. DDT does not immediately kill the insects. It takes several hours to kill them. Ref: Park's Textbook of Preventive and Social medicine, 19th edition, Page 637.