Insecticide Resistance in Heliothis Armigera (Hübner) (Lepidoptera: Noctuidae) in the Namoi Valley of New South Wales, Australia

Heliothis armigera damaged cotton in the Namoi Valley in summer‐autumn 1973. In laboratory studies larvae exhibited several hundredfold resistance to DDT, 15‐fold to DDT/chlorcam (1:2) mixture and 30‐fold to endrin compared with a susceptible strain from Bathurst. The Namoi Valley larvae were found to be 5 times less susceptible than Bathurst larvae to parathion methyl, a difference which may be no more than normal variation between non‐resistant strains. No resistance to insecticides was demonstrated in H. punctigera Wallengren from the Namoi Valley.