The recent sequencing of the honey bee (Apis mellifera) genome has revealed that bees have among the smallest repertoire of cytochrome P450 monooxygenase genes of any insect--only 46 sequences, compared to 89 in Drosophila melanogaster and 111 in Anopheles gambiae. Other insects are known to withstand exposure to natural toxins and gain pesticide resistance through elevated metabolic detoxification made possible by the P450 family of enzymes. There are two explanations for the low P450 number in the honey bee. First, haplodiploidy could be the cause, because selection for P450s associated with resistance occurs directly on hemizygous males, leading to more rapid fixation of these genes. Second, eusociality in bees, and the high level of nest homeostasis eusociality provides, could insulate the queen from exposure to toxins, making P450-mediated detoxification less critical to colony survival. The sequencing of the genome of the haplodiploid, but solitary, jewel wasp (Nasonia vitripennis), and its 90 encoded P450s, has made clear that the social behavior and the well regulated nest environment of the eusocial honey bee may be the principal factor in the low number of P450 genes encoded by the honey bee genome.