Examples of behavioral diversity and evolution are plentiful, yet we still know relatively little about the molecular mechanisms of behavioral adaptation. How many and which genes contribute to ecologically-important behavioral variation? Do behavioral differences arise from structural changes (e.g. circuit structure), functional changes (e.g. neurophysiology), or both? Are certain systems—such as sense organs or neuromodulators—predisposed to be targets of evolutionary change? To address these questions, I use an integrative approach that combines a naturalist’s enthusiasm for animal diversity and evolution with modern molecular and genetic tools. My research takes advantage of dramatic natural differences in the behavior of two subspecies of Aedes aegypti mosquitoes, including host-preference behavior and hatching behavior.