Generalist (polyphagous) herbivores can feed and reproduce on many different plant species and include some of the most pesticide resistant and notorious pests in agriculture. An evolutionary link between host plant range and the development of pesticide resistance has been suggested. Although crucial for devising efficient crop protection strategies, the mechanisms underlying rapid adaptation are not well understood, especially in generalists. The spider mite Tetranychus urticae is a global pest known to feed on 1,100 different hosts from 140 plant families, including most major crops. With experimental advances and new tools developed for T. urticae, we are now poised for fundamental advances in understanding the molecular genetic make-up of adaption in generalist pests. A core set of adaptation genes will be validated by functional expression and high-throughput interaction assays. Further validation will come from the using SYNCAS, a CRISPR/Cas9 based method developed by my group to efficiently edit genes in spider mites and other difficult to transform animals.