Increased detoxification of insecticide is a common method of insecticide resistance. Despite this commonality, the molecular changes that are responsible are for are generally poorly understood. Often little is known beyond the involvement of particular enzyme families in the resistance phenotype or some number of overexpressed detoxification genes that may be involved. The availability of forward genetic studies in pest species will prove invaluable to advancing our understanding of resistance and insecticide toxicology in general. We use a quantitative trait mapping method called bulk segregant analysis (BSA) to determine the basis of a multigenic pyrethroid resistance phenotype to the known target-site of pyrethroids, the voltage-gated sodium channel, and a cluster of cytochrome P450s (CYPs) on chromosome 5. Structural variant calling using long read sequences indicates the area linked to resistance on chromosome 5 is structurally complicated in the resistant strain, and RNA-seq data indicates overexpression of 8 CYPs at this locus. The BSA mapping results are supported by linkage mapping of resistance with known morphological makers and synergist bioassays that indicate involvement of esterase and CYP-mediated detoxification in the resistance phenotype.