County to conduct mosquito larvicide drop to fight West Nile virus

SAN DIEGO — The San Diego County Department of Environmental Health was gearing up Tuesday for another attempt at killing mosquito larvae, this time to combat West Nile virus.

The health department is scheduled to make the seventh drop of a solid larvicide on local waterways Wednesday to kill mosquito larvae before they can grow into adult mosquitoes, potentially spreading the virus.

The aerial drops are not related to recent hand-spraying done in four San Diego neighborhoods to kill adult, invasive Aedes mosquitoes to prevent the spread of the Zika virus.

Aerial larvicide drops have been part of the county’s West Nile virus prevention measures for several years. The county conducts the operations about once a month during mosquito season, precisely dropping batches of solid, cereal-sized larvicide on about 48 local waterways, including ponds, rivers and wetlands.

Health officials stressed that 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.