Maricopa County Environmental Services Department has an extensive mosquito-trapping program that enables staff to identify areas where there is mosquito activity and to detect any mosquito-borne diseases.
Various types of mosquito traps are set up throughout the county that collect mosquitoes for testing. These mosquitoes are pooled together, by species, into groups of 1-50 mosquitoes. This collection of mosquitoes is called a mosquito pool. The female mosquitoes are separated and are then processed and tested for West Nile virus (WNV) and Saint Louis Encephalitis (SLE). Traps with pools or samples that test positive for WNV and SLE are listed in graphics below.