Sacramento‑Yolo mosquito district warns invasive day‑biting species are established in West Sacramento, launches sterile‑male pilot

At the July 16 West Sacramento City Council meeting the Sacramento‑Yolo Mosquito and Vector Control District briefed the council on this year’s mosquito season and on new tools it is using to fight an invasive day‑biting species established in parts of the city.

Alus Maria Robles, public information officer for the district, said West Nile activity has been low so far but that local conditions — hot spells and standing water — could change that. She told council members the district uses traps and laboratory testing to track virus activity and that control decisions are based on where infected mosquitoes or birds are detected.

Robles said the more immediate concern for West Sacramento is an invasive species first detected in the district in 2019 that breeds in very small containers and bites aggressively during the day. “This mosquito is a day‑biting mosquito…it breeds in very small containers. Even a teaspoon of water is enough,” she said, adding that the species can increase the risk for dengue if infected travelers are bitten locally.

The district described current control tactics — public education, source reduction, targeted spraying, use of larvivorous “mosquito fish” and trapping/surveillance — and outlined a recently launched sterile‑insect technique (SIT) pilot in South Natomas. Robles said the SIT releases sterile males carrying Wolbachia bacteria; sterile males do not bite and when they mate with wild females the eggs do not hatch. The technique, she said, is being evaluated and will continue through October; Fresno trials previously reported a 95% reduction in mosquito counts.

Council members asked about how fish releases and agricultural spraying are coordinated in rice and canal zones and whether the district sends neighborhood notifications when it plans truck or aerial spraying. Robles said the district works with local agencies and field technicians to place fish in ponds, troughs and rice fields and that email notifications are available through fightthebite.net to warn residents by ZIP code when spraying is scheduled.

Robles offered a free home inspection service for residents who report mosquito problems and said the district will provide outreach materials and repellent wipes for city events. She also acknowledged West Sacramento’s board representative, Janelle Deroche.

The council did not take action; the presentation was informational. The district encouraged residents to report mosquito infestations via the district website and to remove standing water weekly to reduce breeding.

Ending: The district left materials and offered to work with city Parks & Recreation staff on outreach at events; it will continue surveillance and report back on the SIT pilot’s results and any detected increases in West Nile or other virus activity.