Products used to control mosquito larvae are called larvicides. The District mainly uses three different types of larvicide, plus one mosquito predator:
BVA-2 Oil: A refined petroleum distillate that breaks down in a few days. It is applied to the surface of standing water and causes mosquito larvae to drown.
Mosquito larvae are only found in standing water, so mosquito larval control products are applied to water. These products are often applied by hand to small areas, such as backyard ponds and catch basins.
The District uses a helicopter to apply solid granular larvicide to larger areas where there is dense vegetation or where applying the product on foot might harm sensitive wildlife and habitats. Currently, a helicopter is used at Annex Lake, Mills Field, and Sharp Park golf course.
Even very small amounts of water can provide enough space for mosquito larvae. Some mosquito species need as little as a bottle cap full of water to reproduce!
How long does it take for mosquitoes to breed?
Under the right conditions, it can take as little as a week for mosquito larvae to emerge as adults. In general, warmer weather means faster development.
The District currently uses a helicopter to treat three freshwater marshes: Annex Lake (Stanford property), Mills Field (SFO property), and Sharp Park Golf Course.
At each of these locations, only the water is treated.
When do helicopter treatments occur?
Helicopter treatments are scheduled as needed. You can find upcoming treatments listed on our calendar. We conduct an average of four treatments per year.
