Flooding at Sauvie Island
Flooding usually occurs annually with the spring freshets and can produce millions of mosquitos per acre. These mosquitoes can fly up to 20 miles and are highly migratory. These mosquitos are controlled by air using a helicopter.
Storm Drains are an important part of mosquito control. They are a main source of Culex Pipiens mosquito, which is a primary vector of West Nile Virus. One drain can produce thousands of mosquitos.
Watering troughs can be controlled using gambusia affinis, also known as the mosquito fish. Watering troughs produce various species of mosquitoes, all of which can transmit West Nile Virus and Western Equine Encephalitis.
Tires can be one of the first sources of mosquito breeding. They breed a species of mosquito called Aedes Sierrensis. This species of mosquito originally laid its eggs in tree holes, but readily adapted to tires as a source to lay its eggs.
Water Retention Pond
In recent years stormwater retention ponds have become a serious problem. These sites are man-made to hold stormwater in newer housing developments. These sites breed many species of mosquitos and left untreated can produce mosquitoes year around.