In 1974, following the occurrence of DDT resistant H. armigera, a resistance monitoring program for Heliothis spp. was started at the Tamworth laboratories of the Department of Agriculture, NSW. All insecticide management decisions require a solid platform of reliable data and this can only be achieved by a long-term commitment to pesticide studies. Resistance monitoring has involved obtaining of baseline susceptibility data for H. armigera and H. puntigera, monitoring of changes in resistance levels and cross resistance patterns. The routine monitoring and testing programs at Tamworth has extended naturally to studies in depth of resistance mechanisms all d genetics, since they are basic to a fuller understanding of resistance problems, and to the development of practical responses.