Mosquitoes bite humans and animals, causing itchy welts on the skin. Some also spread diseases, including West Nile virus, malaria and Zika virus. Even mosquitoes that don’t directly spread disease can be a source of infection if a person scratches their bites and the wound becomes infected.
Mosquitos are drawn to light, so a well-lit backyard can be an attractive area for them. They also breed in standing water, such as puddles, birdbaths and ponds.