All insecticide management decisions require a solid platform of reliable data and this can only be achieved by a long term committment to pesticide studies, obtaining baseline susceptibility data and monitoring of changes in resistance levels. In this paper, a summary of findings from this resistance monitoring program from 1974 to 1988 will be presented. Insecticides screened have been pyrethoids, endosulfan, carbamates and organophosphorous compounds. At the same time, research has been conducted to develop innovative bioassay methods for chemicals with novel modes of action or unusual methods of entry into Heliot:h.is spp.