Mosquitoes typically breed and lay their eggs in water clogged with such vegetation as waterlettuce, hydrilla, waterhyacinth, and cattail, authors Patrick O'Connor-Marer and Kathy Keatley Garvey wrote in their book, Aquatic Pest Control. Garden pools or backyard ponds teeming with waterlilies (above) and other aquatic plants are also a favorite spot. (Photo by Kathy Keatley Garvey)