Mosquitoes seek their host in response to a combination of chemical and physical stimuli, including carbon dioxide plumes, certain body odors, warmth, and movement.

Anopheline mosquitoes feed most frequently at night and occasionally in the evening, or in heavily shaded or dark areas during the early morning. During feeding, the mosquito injects a minute amount of salivary fluid into the host to increase blood flow to the area. Sporozoites are transmitted to the host in the salivary fluid.

Anopheles mosquitoes are readily distinguished from other genera by their characteristic stance, in which they appear to be standing on their heads. (Most mosquitoes hold their bodies relatively parallel to the surface on which they are resting.) After feeding, some engorged females seek out cool and humid areas of a house, such as walls and the undersides of furniture, while others find dark, secluded spots outdoors near the ground. Some mosquitoes have modified their resting behavior so as to avoid surfaces treated with pesticides.

FIGURE 2-5 Ideal larval development site for some anopheline mosquitoes. (Photo courtesy of Dr. Pedro Tauil, IOM Malaria Committee member)