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Posted on: August 30, 2018

County treats San Dieguito Lagoon for mosquitoes


The County of San Diego applied larvicide to San Dieguito Lagoon on Wednesday as a routine measure to control mosquitoes. The lagoon was one of nearly 50 locations across the region to receive the treatment, in which a helicopter drops granular larvicide into hard-to-reach waterways that are suspected of breeding mosquitoes.

The active ingredient of the larvicide is a biological material specifically targeted to the larval stages of mosquitos. Larvicide presents no health risks to people, wildlife or pets.

A salt marsh mosquito that breeds in coastal lagoons has an irritating bite but is not known to transmit dangerous diseases such as West Nile virus, a county spokesman said.

No human cases of West Nile Virus have been reported in the county this year. Nor has the disease been detected in birds, which are the main carriers. Last month, County technicians detected West Nile virus for the first time this summer in a batch of mosquitoes caught during routine trapping in Santee.

Last year, two San Diego County residents tested positive for West Nile virus; both recovered. For information regarding West Nile Virus in San Diego County, please visit the County’s West Nile Virus Web page.

The County’s Vector Control Program coordinates aerial larvicide applications every summer and also employs technicians to treat drainage ditches, unmaintained swimming pools and ponds. Any place where water can stand for a week can become a breeding source. Homeowners are asked to check their property for standing water that may have collected in gutters, toys and pottery. Be sure rain barrels are well-screened.

Public health authorities also urge residents to apply repellent, wear long sleeves and pants when outdoors or stay inside at dawn and dusk, when mosquitoes are most active.

To report mosquito activity or request an inspection, contact the Vector Control Program at (858) 694-2888 or

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