The mosquito is a known vector of encephalitis. It is a widespread pest from Florida, where it is known as the 'glades mosquito', to New York. Scattered populations exist across the United States westward to California. The species is found in Mexico, Central America, the Caribbean and South America to Argentina. Psorophora columbiae reaches its greatest abundance in the rice growing areas of the southwestern U.S. where astronomical numbers, similar in magnitude to the production of saltmarsh mosquitoes, may occur.