Insects exhibit diverse resource-exploitation strategies, including predation, herbivory and parasitism. The ecological and evolutionary factors that influence the resource selection of some insects (e.g. herbivores) have been extensively investigated because of their agricultural importance. By contrast, there has been little investigation of the selective forces that mediate host choice in haematophagous insects, despite their importance as vectors of disease. Here, we review potential determinants of host species choice in mosquitoes, the most important insect vectors of human disease, and discuss whether these could be manipulated to yield new disease-control strategies based on vector behavioural change.