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Pesticide spraying set for July 14 and 15 in more La Mesa neighborhoods
By Miriam Raftery
July 11, 2025 (La Mesa) – Concern over West Nile virus in the La Mesa and Rolando areas has ramped up, after County Vector control tested nearly 2,000 mosquitos in 165 batches in these areas.
West Nile virus found in 37 batches of mosquitos tested in Roland and La Mesa
“In this area, 37 batches have tested positive for West Nilie virus, Gig Conaughton, communication specialist for San Diego County, told East County Magazine.
The positive tests were in La Mesa and the San Diego portion of Rolando.
Mosquitos were also tested in Lemon Grove, with no West Nile virus detected there.
Spraying dates and locations
Pesticide spraying will be done Monday and Tuesday, July 14 and 15, between 1 a.m. and 6 a.m.in the La Mesa areas shown on the map at left and at the County's Adult Mosquito Control site.
The Rolando area was previously sprayed, but after more positive test results, spraying has been extended for Monday and Tuesday to cover additional parts of La Mesa including Eastlake, areas along El Cajon Boulevard and as far north as Parkway Drive.
La Mesa information session Saturday morning, July 12
Vector Control staff will answer questions at an information session this Saturday, July 12 at the La Mesa Library, 8074 Allison Avenue, from 10 a.m. to 12 p.m.
A statement from La Mesa says, The City of La Mesa appreciates the County’s efforts in helping protect the health and safety of our residents.”
Flower-based pesticide to be used; precautions to take
The pesticide. AquaDuet, is based on a natural substance found in Chrysanthemum flowers, Conaughton says.
“AquaDuet has been approved by the Environmental Protection Agency, and is found to pose low risks to people and pets. People who are concerned about the treatment can stay indoors and close windows during the treatment period...The pesticide will dissipate after about 30 minutes and people can resume normal activities.
Beekeepers and those with insects kept outdoors are encouraged to shelter hives and habitats during treatments.
West Nile virus facts
There have been no reported human cases in San Diego County this year. In 2024, the County reported 2 cases. However, West Nile virus remains a potentially deadly threat.
Symptoms may include fever. headaches, body aches, joint pains, vomiting, diarrhea or rash. in rare cases, West Nile virus can be fatal. A resident of Mt. Helix died of West Nile virus several years ago.
If you have symptoms, seek medical care.
The virus is transmitted by Aedes Aegypti mosquitos, an invasive species that is smaller than native species. It bites during the day and can breed in as little as a thimbleful of water, even indoors. In the tropics, these mosquitos also carry Zika Virus and Yellow Fever, though those diseases have not been found in mosquitos in San Diego County.
Steps to stay safe
County officials said people should continue to follow the County’s “Prevent, Protect, Report” guidelines to protect themselves from mosquitos. Those include finding and dumping out standing water around homes to keep mosquitos from breeding.
Prevent mosquito breeding
Dump out or remove any item inside or outside of homes that can hold water — whether from rain or landscape irrigation. Those things can include plant saucers, rain barrels, buckets, garbage cans, toys, old tires and wheelbarrows.
Mosquitofish, 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, para-menthane-diol, 2-undecanone 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, unmaintained green swimming pools, and other mosquito-breeding sources, as well as dead birds — including crows, ravens, jays, hawks and owls — to the County Vector Control Program by calling (858) 694-2888 or emailing vector@sdcounty.ca.gov(link sends e-mail)
More information
For more information, visit the County's Adult Mosquito Control webpage or Fight the Bite page . You can also call 858-694-2888 or email vector@sdcounty.ca.gov with questions.
Here is a link to the AquaDuet manufacturer’s Frequently Asked Questions.
You can find the Vector Control’s most recent data on testing in tables on the County’s West Nile virus activity webpage. Staff will be answering questions over the weekend.
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