Across insect genomes, the size of the cytochrome P450 monooxygenase ( CYP ) gene superfamily varies widely. CYP ome size variation has been attributed to reciprocal adaptive radiations in insect detoxification genes in response to plant biosynthetic gene radiations driven by co‐evolution between herbivores and their chemically defended hostplants. Alternatively, variation in CYP ome size may be due to random “birth‐and‐death”...