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Posted on: June 1, 2021

County begins mosquito-fighting aerial larvicide drops

Helicopter flies above waterway

The County of San Diego is set to begin aerial applications of larvicide at San Dieguito Lagoon and other waterways this week as a routine measure to control mosquitoes.

The lagoon is one of nearly 50 locations across the region to receive the treatment, in which a helicopter drops granular larvicide into hard-to-reach areas 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.

The County’s Vector Control Program coordinates larvicide applications every summer and also employs technicians to treat drainage ditches, unmaintained swimming pools and ponds.

Depending on conditions, the treatments will occur every three to four weeks or as needed during the mosquito season.

 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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