Banner image showing a close-up mosquito on the right with the text 'SIT Program' on a green and yellow background.

INNOVATIVE MOSQUITO CONTROL: PROTECTING OUR COMMUNITY

The invasive mosquito Aedes aegypti is spreading across California, including Sacramento and Yolo counties. This mosquito isn’t just annoying; it can carry and spread dangerous viruses including: dengue, Zika, and chikungunya. Since our first detections of Aedes aegypti, we’ve been working to control their spread. They were discovered for the first time in Rosemont in 2021 and have since expanded rapidly in the area. (For more information about invasive Aedes mosquitoes, click here.)

The spread of the Aedes aegypti mosquito in the Rosemont area, 2021-2025

Areas shaded green have fewer detections, while areas shaded red have the highest concentrations

Heatmap showing concentrations of Aedes aegypti mosquito detections in the Rosemont area, with the highest activity centered around Rosemont Park and surrounding neighborhoods.

FIGHTING INVASIVE MOSQUITOES WITH NEW TECHNOLOGIES

Sterile Insect Technique (SIT): A proven, environmentally friendly method to stop mosquitoes from reproducing that was developed more than 60 years ago and is successfully used by many agencies for multiple insect species. While there are several SIT approaches available, the District plans to use the Wolbachia method in Rosemont. (For more information on other forms of SIT, click here.)

What Is Wolbachia? 

Wolbachia is a naturally occurring bacteria found in many insects including butterflies, dragonflies and some mosquitoes – but not in Aedes aegypti – that can lead to sterility in female mosquitoes.

How Wolbachia Works: Male mosquitoes (which do not bite) carrying Wolbachia are released into a neighborhood where they mate with wild females that do not carry Wolbachia. This mismatch in Wolbachia status results in non-viable eggs. Because female mosquitoes only mate once, they become sterile and will not add to the invasive population. The goal is to release enough Wolbachia-carrying males to mate with all wild females, leading to a dramatic drop in Aedes aegypti populations over time. (To watch a detailed video of the Wolbachia process, click here.)

SAFE AND TARGETED

This method only affects the Aedes aegypti mosquito species, leaving other insects unaffected. Since invasive Aedes are a public health threat and continue to expand throughout Rosemont, we are conducting an SIT program and will regularly release sterile males carrying Wolbachia from July 2026 through October 2026. 

The Wolbachia SIT Process

An image of a Wolbachia-infected adult male mosquito where Wolbachia is represented by green dots on the mosquito's body with the caption "Wolbachia-infected Male Mosquito." An arrow points to an adult female mosquito with the caption "Wild (uninfected) female." Beneath these two mosquitoes is a third adult female mosquito with the caption "eggs won't hatch."

WHAT ROSEMONT RESIDENTS CAN EXPECT 

  • District staff will release only male mosquitoes – which do not bite – on a weekly basis in designated areas of Rosemont, so you may see more mosquitoes.
  • Staff will be going door to door in your area, distributing information about our SIT program
  • Staff will be setting traps in your area to monitor and evaluate the results of our SIT efforts in the area
  • Since other biting mosquito species are still active in the area, residents should continue to protect themselves by using effective mosquito repellent or wearing long sleeves and pants when outdoors.

To request a free backyard inspection, click here.

SIT Program in Rosemont

Area represented shows all potential surveillance, door-to-door communication, and SIT release sites.

Map of the Rosemont area in Sacramento showing the Sterile Insect Technique (SIT) program outlined in orange. The area includes Rosemont Park, Rosemont Square, Rosswood, Rosemont Downs, Timberlane, Gold Creek, and surrounding neighborhoods.