Gravid Traps are a type of mosquito trap that uses water mixed with rabbit feed and yeast as an attractant for female mosquitoes looking for a suitable place to lay their eggs. When the pregnant, or gravid, mosquito attempts to lay their eggs in the nutrient rich water inside of the tub, they are sucked up into a tube by a fan. These traps are placed overnight and are especially important for collecting blood fed female mosquitoes who can be tested for arboviruses, such West Nile Virus and St. Louis Encephalitis.