County Drops Larvicide to Fight West Nile Virus

San Diego County’s environmental health department plans to conduct its seventh aerial drop of a solid larvicide on local waterways Wednesday to fight West Nile virus by killing mosquito larvae before they can grow into adult mosquitoes.

The aerial drops are not related to recent hand-spraying done in four neighborhoods to kill adult, invasive Aedes mosquitoes.

The aerial larvicide drops have been part of the County’s West Nile virus prevention measures for several years. The County conducts the drops roughly once a month during mosquito season, precisely dropping batches of solid, cereal-sized larvicide on roughly 48 local waterways, including ponds, rivers and wetlands. The larvicide contains a bacterium that doesn’t hurt people and pets, but kills mosquito larvae.

So far this year, five San Diego County residents have been confirmed as testing positive for West Nile virus. In the 2015 season, 45 San Diego County residents tested positive, 44 of which did so after mid-September.

County officials reminded people that they can help protect themselves by following the County’s “Prevent, Protect, Report” advice.

Prevent Mosquito Breeding: Dump out or remove any item inside or outside of homes that can hold water, such as plant saucers, rain gutters, buckets, garbage cans, toys, old tires, and wheelbarrows. Mosquito fish, available for free, may be used to control mosquito breeding in backyard water sources such as unused swimming pools, ponds, fountains and horse troughs.

Protect Yourself from Mosquito Bites: Protect yourself from West Nile virus by staying inside when most mosquitoes are most active, at dusk and dawn. Wear long sleeves and pants or use repellent when outdoors. Use insect repellent that contains DEET, picaridin, oil of lemon eucalyptus or IR3535. Make sure screens on windows and doors are in good condition and secured to keep insects out.

Report Dead Birds and Green Swimming Pools: Report dead crows, ravens, jays, hawks and owls, and green swimming pools to environmental health’s Vector Control Program by calling (858) 694-2888 or emailing vector@sdcounty.ca.gov. Also report if you are being bitten by mosquitoes during daylight hours, or if you find mosquitoes that match the description of Aedes mosquitoes by contacting the Vector Control Program at (858) 694-2888.

For more information about West Nile virus, go to San Diego County’s “Fight the Bite” website.

Gig Conaughton is a communications specialist with the County of San Diego Communications Office. Contact