In the course of their studies, Vinauger and his colleagues exposed small populations of mosquitoes to various feeding trials, scheduled for the early morning and the early evening—the insects’ peak hours for seeking out blood meals. In the first trial, the mosquitoes were contained in a glass tube, and on the other side was a fine mesh was a vessel of blood, warmed to a body-temperature 98.6°F. After allowing the mosquitoes to feed on the blood through the mesh, the researchers exposed them to the smell of DEET—which did not deter their feeding behavior. The blood and the scent of DEET were then removed and the mosquitoes eventually abandoned the mesh. Next, the smell of DEET was reintroduced, but the blood was not. Nonetheless, even in the absence of the blood reward, more than 60% of the insects returned to the mesh, expecting a meal.
