The preferred long-term and most cost-effective vector control strategy is to eliminate larvae before they become adults. Catch basins are a major known source of Culex pipiens, a species of mosquitos that transmits West Nile Virus. While Culex mosquitos can develop in a variety of freshwater habitats, the greatest concentration of Culex breeding is in the estimated 60,000 catch basins found in the District, all of which are treated annually. The stagnant water that sits in a catch basin most of the summer is a prime breeding site for these species. Click here for product information.