HAYWARD, CA August 13, 2026 - On August 12 multiple invasive Aedes aegypti mosquitoes were found in the Irvington neighborhood of Fremont. In response, Alameda County Mosquito Abatement District staff have increased mosquito monitoring and control efforts in the area and will conduct a truck-mounted larval treatment on August 14th during early morning hours to prevent additional adult mosquitoes from emerging. 

Application details: 

• Insecticide: VectoBac® WDG 
• Active ingredient: Bacillus thuringiensis subspecies israelensis (Bti) 
• Bti is a naturally occurring soil bacterium that produces proteins that specifically target and kill mosquito larvae, as well as the larvae of black flies and midges. It is non-toxic and non-pathogenic to humans, birds, fish, mammals and beneficial insects, including pollinators. 
• Method: Truck-mounted ultra-low volume sprayer 
• Date & Time: August 14th (weather permitting), between 3:00 a.m. - 6:00 a.m. 
• Residents are encouraged to stay indoors during these hours and to close windows and doors. 
• Location: The treatment area is between Fremont Blvd/Washington Blvd and Blacow Rd, bounded by Grimmer Blvd and BART tracks. (see map below). 
• Additional details: The treatment may leave a light residue on outdoor surfaces. The residue will wash away with water and it is safe to drain into the sewer. 

Aedes aegypti is an invasive mosquito that can transmit diseases such as dengue, chikungunya, Zika, and yellow fever. Like all mosquitoes, Aedes aegypti requires standing water to complete its life cycle but can develop in as little as a bottle cap of water. Eliminating standing water is the most effective way to prevent mosquitoes. Covering or treating water with mosquito-specific larvicides is a good option for water that cannot be dumped or drained. 

"By conducting a larval-based treatment on August 14th, we aim to reduce the number of adult Aedes aegypti mosquitoes by interrupting their life cycle at the larval stage and finding hidden sources of standing water," says Community Liaison Liz Martinez. "Residents can help by checking in and around their homes for standing water found in plant saucers, buckets, bird baths, yard litter, and any container that can hold as little as a bottle cap of water. Mosquito control is a community effort, and we appreciate the public’s support and cooperation as we continue our efforts in the area."

Community cooperation is essential for effective mosquito control. Residents are encouraged to:

• Report mosquito activity in your neighborhood to the District. 
• Eliminate standing water where mosquitoes breed, including outdoor containers, plants, unmaintained swimming pools, and other hidden sources. 
• Protect yourself from mosquito bites by wearing long, loose-fitting clothing, using EPA-registered insect repellent, and ensuring window and door screens are in good repair. 

The District remains committed to protecting public health through ongoing mosquito surveillance, larval control, and community education throughout Alameda County.

The treatment area is highlighted in orange and between Fremont Blvd/Washington Blvd and Blacow Rd, bounded by Grimmer Blvd and BART tracks. (see map below).