Health

County to Conduct First Larvicide Drop of 2022

Helicopter dropping larvicide
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San Diego County is scheduled to carry out its first routine aerial larvicide drop of the year Wednesday and Thursday on more than four dozen waterways, to help stop mosquitoes from potentially spreading disease like West Nile virus.

County Vector Control officials are also reminding people to help protect themselves from mosquitoes in and around their homes by finding and dumping out standing water to keep the pests from breeding.

The County has used helicopters to drop batches of solid, granular larvicide on hard-to-reach rivers, streams, ponds and other waterways roughly once a month from April through October since West Nile virus arrived in the early 2000s.

The larvicide does not hurt people or pets but kills mosquito larvae before they can grow into biting mosquitoes.

West Nile virus is mainly a bird disease. However, mosquitoes can pass the potentially deadly virus on to people by feeding on infected birds and then biting people.

West Nile virus’ effect has been relatively mild in San Diego County in the past few years. Three or fewer people have tested positive annually since 2017. But it can still be dangerous and people should avoid mosquitoes.

In 2016, 22 people in San Diego County tested positive, 20 got sick and two people died, according to California’s Department of Public Health. In 2015, 44 people tested positive, 42 got sick and six people died in the county.

Vector Control officials said there have been no West Nile virus detections to date in San Diego County this year, not in mosquito pools, animals or people.

The larvicide drops are just one part of Vector Control’s yearly mosquito control program. County Vector Control also treats another roughly 1,500 potential mosquito-breeding areas each year by hand, gives out free mosquito-eating fish to the public, tracks down and treats neglected swimming pools, tests dead birds for West Nile virus and monitors cases for other potential mosquito-borne illnesses.

Public has Important Role to Play

Protecting against mosquitoes has required more help from the public in recent years because of the appearance of a number of types of invasive Aedes mosquitoes that can potentially transmit diseases not naturally found here, including Zika, dengue and chikungunya. While native culex mosquitoes that can transmit West Nile virus breed in larger water bodies reached by the County’s larvicide drops, invasive Aedes mosquitoes prefer to live and breed around people’s homes and yards.

County Vector Control officials said the best way people can protect themselves from mosquitoes is to follow their “Prevent, Protect, Report” guidelines.

Prevent mosquito breeding

San Diego County residents may be more vulnerable to being bitten by mosquitoes around their homes now because many have been spending more time at home because of the coronavirus pandemic. So, remember to 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 by contacting the Vector Control Program, may be used to control mosquito breeding in backyard water sources such as stagnant swimming pools, ponds, fountains and horse troughs.

Protect yourself from mosquito bites

Protect yourself from mosquito-borne illnesses by wearing long sleeves and pants or use insect 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 possible mosquito activity and dead birds

Report increased mosquito activity, or stagnant, green swimming pools and other mosquito-breeding sources, as well as dead birds — dead crows, ravens, jays, hawks and owls — to the County Department of Environmental Health and Quality’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 look like invasive Aedes mosquitoes — small, black with white stripes on legs and backs — by contacting the Vector Control Program at (858) 694-2888.

For more information about mosquito-borne illnesses, go to San Diego County’s “Fight the Bite” website. Here are some tips to help you keep your yard from becoming a mosquito breeding ground.

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