This thesis is an investigation of the detection, documentation, and spatial analysis of insecticide resistance in southern Ontario Colorado potato beetle populations from 1995 to 1998. Three types of bioassay were evaluated: leaf-dip and diet-incorporated feeding bioassays, and a treated filter-paper contact bioassay. Feeding bioassay methods test insecticides that demonstrate toxicity through ingestion but are more time-consuming and complicated than the filter-paper method. The diet-incorporated method was the most practical feeding bioassay for large-scale surveys. Only the leaf-dip method worked with 'Bacillus thuringiensis'. Resistance was seen in all locations to cypermethrin, azinphos-methyl, endosulfan, and oxamyl. No resistance was found to imidacloprid and lambda-cyhalothrin. Baseline susceptibility was determined for fipronil, pyrrole-3-carbonitrile and spinosyn A, D. Quick bioassay methods only provide estimations of actual tolerance levels, but are practical for screening many populations. Introduction of GIS technology into resistance monitoring programmes provides ease of data management, presentation and dissemination.