All are true regarding DDT, EXCEPT:

DDT (Dichloro diphenyl trichloroethane) ♦It was first synthesized in by a German chemist, Ziedler. ♦Its insecticidal action was described by Paul Muller. ♦It is primarily a contact poison. ♦It acts on nervous system of insects. ♦It takes several hours to kill the insect. ♦The residual action of DDT may last as long as 18 months. ♦It has no repellent action on insects. ♦As a residual spray, DDT is applied at a dosage of 100–200 mg/ sq. foot area. ♦The formulation of choice is a 5 % suspension, 5–10 % strength for the control of lice, fleas, ticks, and bugs.