The winter months are passing by and adult mosquito activity will soon begin to increase.  In Alameda County mosquitoes breed year-round.  However, the majority of our native mosquito species are still in their larval form during the winter months.  In an effort to reduce springtime mosquito populations, our staff continue to treat for larval mosquitoes throughout the winter months.  Targeting mosquito larvae is the most effective way to control mosquitoes.  So remember, dump and drain any standing water on your property to keep mosquitoes from breeding in your yard!   Read more about our mosquito control program.

District employees have been busy during the last few months treating larvae of our main winter mosquito

Argos are used to treat mosquito larvae in several marsh areas

species, Aedes squamiger, Aedes washinoi, and Culiseta inornata. Increased rain levels this winter created sources of standing water where mosquitoes could breed that did not exist in previous years.  Each rain event can also trigger a new hatch of Aedes mosquito larvae.  Our native Aedes mosquitoes can be found breeding in a variety of habitats, such as saltwater marshes, freshwater marshes, flooded woodlands (especially those that contain willow trees), and even tree holes (rotted out cavities in the trunk of a tree). Treatments of larval  Aedes sierrensis, the treehole mosquito, will continue over the coming month. Treehole mosquito adults typically begin to emerge around the Spring equinox.  More information on Alameda County mosquito species.

Surveillance of adult mosquito populations also continued throughout the winter months.  New Jersey light traps (pictured to the right) are distributed among the county and checked on a weekly basis.  Overall, the number of adult mosquitoes in Alameda County right now is low.  As the season begins to change, more mosquito surveillance traps will be placed in areas with known mosquito breeding sources to monitor mosquito activity.  In addition, surveillance for invasive mosquitoes such as Aedes aegypti and Aedes albopictus (the mosquitoes capable of transmitting dengue, chickungunya, and Zika) will expand as well.  More about District surveillance efforts.