County to Hand-spray Escondido Neighborhood in Travel-related Zika Case

County Vector Control crews plan to hand-spray an Escondido neighborhood to kill invasive Aedes mosquitoes and prevent them from potentially spreading the Zika virus after finding them near a person who contracted Zika outside the country.

County crews went door-to-door in the area Tuesday to notify residents in person, leave door hangers and show people how to prevent mosquitoes from breeding inside and outside their homes.

Vector Control plans to hand-spray the area Thursday, weather permitting.

This will be the eighth neighborhood that Vector Control has had to hand-spray this year to protect the public health.

The area to be hand-sprayed is roughly 17 acres in size, includes 109 units and is bordered on by Rimrock Drive on the north and East El Norte Parkway on the south.


Two invasive species of Aedes mosquitoes in San Diego County can transmit tropical diseases like the Zika virus, dengue and chikungunya if they first bite an infected person. No invasive Aedes mosquitoes have tested positive for carrying any diseases in San Diego County to date.

County officials have continued to urge people to protect themselves from mosquitoes and take simple steps to prevent them from breeding in the first place — mainly by finding and dumping out any standing water inside and outside their homes.

Invasive Aedes mosquitoes are known as “urban” mosquitoes because they prefer to live and breed around people, in backyards and even inside homes. Invasive Aedes mosquitoes can breed in as little as a thimble-full of water, and females lay between 100 to 300 eggs at a time.

One big difference between invasive Aedes mosquitoes and native mosquitoes is their biting habits. Both invasive Aedes and native culex mosquitoes — which can transmit West Nile virus if they bite infected birds and animals — like to bite around dusk and dawn.

But invasive Aedes mosquitoes also bite during daylight hours. Culex mosquitoes feed at night, not during daylight.

For a better look at the differences between invasive Aedes mosquitoes and native culex mosquitoes, see our “Tale of the Tape.

Trained County technicians will use ultra-low-volume backpack sprayers to apply Pyrenone 25-5, a pesticide approved for use by the Environmental Protection Agency. The product is made from chrysanthemums, poses low risks to people and pets and dissipates in roughly 20 to 30 minutes. However, the County is instructing residents in spray areas that they can avoid or minimize their exposure to the pesticide by taking simple steps:

  • Stay inside and bring pets indoors if possible
  • Close doors and windows, and turn off fans that bring outdoor air inside the home
  • Cover ornamental fishponds to avoid direct exposure
  • Rinse fruits and vegetables from your garden with water before cooking or eating
  • Wipe down or cover outdoor items such as toys and cover barbecue grills
  • Beekeepers and those with insects kept outdoors are encouraged to shelter hives and habitats during treatments. Beekeepers are required to register their apiaries with the County’s Department of Agriculture, Weights and Measures to receive advance notice of when a pesticide that may affect bees is applied to blossoming plants in their areas.
  • You may resume normal activities 30 minutes after the treatment

County officials reminded people to follow the County’s “Prevent, Protect, Report” guidelines.

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 by contacting the Vector Control Program, 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 mosquito-borne illnesses by wearing 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 possible mosquito activity

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.

Information about the Zika viruschikungunya, and dengue can be found on theCenters for Disease Control and Prevention’s website.

For more information about mosquito-borne illnesses, go to San Diego County’s “Fight the Bite” website. You can also get more information about how the County works to trap and test invasive Aedes mosquitoes, and hear how the public can help prevent mosquitoes from breeding in the following videos.




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