Proactive Catch Basin Larviciding
Catch basins, also called storm sewers or storm water catch basins, are located throughout the county. Catch basins usually drain well and do not present a problem as far as mosquito breeding; however, some may have structural problems or may be partially blocked, retain water and produce excellent breeding sites for the mosquito vectors of West Nile virus. This is particularly common in older communities in the County.
The Health Department treats catch basins throughout the County with a larvicide, an insecticide used to kill mosquito larvae, in programmed cycles aimed at reducing mosquito populations that breed in this environment. The first treatment cycle typically begins in May each year, with the number and magnitude of each cycle dependent on climatic factors and mosquito surveillance results.
The Department of Public Works and Environmental Services will ensure larviciding of storm water retention ponds countywide where deemed necessary.
The Fairfax County West Nile Virus Surveillance Program will work closely with the Park Authority to manage vector mosquito populations in parks when necessary. Nuisance mosquito breeding sites will not be routinely treated.
In the history of West Nile virus in Fairfax County, particularly in the
past three years when we have had human cases, the use of spray
insecticides against adult mosquitoes has not been necessary. However, if
mosquito surveillance data indicates that the level of West Nile virus
activity poses a significant threat to human health; adult mosquitoes
will be controlled with adulticides.