Twenty-one insecticides were tested for acute toxicity by surface film contact method against the grasshopper, Zonocerus variegatus (L.) in the laboratory. Decamethrin, cypermethrin, lindane o, o-diethyl(p-methyl sulfinyl) p′-phosphorothioate, and dieldrin were highly potent. Moderately potent insecticides were propoxur, bioallethrin, telodrin, isodrin, heptachlor and rotenone. A toxic symptom common to all potent insecticides in the female was the opening and closing of ovipositor valves which remained wide open at death. Five insecticides—dieldrin, telodrin, p, p′-DDT, chlorobenzilate, DMC and chlordimeform induced cannibalism among the treated females.
