Program Information The Orange County Mosquito and Vector Control District (District) is a special district and is one of over 100 agencies statewide specifically dedicated to protecting public health by controlling rats, flies, mosquitoes, Red Imported Fire Ants and other vector related problems. The District's primary concerns are with West Nile virus, flea-borne typhus, and the control of a newly-introduced tropical mosquito Aedes aegypti. These problems are new to our region and have adverse impacts on human heath in the county.