October 3, 2025

HAYWARD, CALIFORNIA – The Alameda County Mosquito Abatement District (the District) is urging residents to inspect their properties for standing water after the recent rain. District staff have detected invasive Aedes aegypti mosquitoes in multiple parts of Alameda County. These mosquitoes are aggressive daytime biters capable of transmitting pathogens that cause Zika virus, dengue, and yellow fever.

Aedes aegypti mosquitoes thrive in warm, wet conditions—exactly what Alameda County has experienced recently due to early fall rains. The District encourages residents to check their yards for standing water and take the following actions:

• Dump out any standing water—even as little as a tablespoon—from items such as buckets, toys, tires, fountains, flower pot saucers, and pet bowls. Report unmaintained swimming pools to the District.

• Scrub or treat items that hold water with dish soap or a 5% bleach solution.

• Cover lawn drains and water collection containers with window screen or a finer mesh material.

• Report any daytime-biting mosquitoes to the District at 510-783-7744.

Aedes aegypti mosquitoes are very small (about ¼ inch), with black bodies marked by pearly white stripes and spots. They lay sticky eggs in any container that holds water—even something as small as a bottle cap. Because of their potential to spread disease and their ability to develop from egg to adult in tiny amounts of water, it is crucial that Alameda County residents work with the District to prevent them from spreading.

Once established, Aedes aegypti mosquitoes can make outdoor activities extremely unpleasant. To learn more about preventing this invasive mosquito in your neighborhood, visit the District’s website: Backyard Checklist

The Alameda County Mosquito Abatement District is committed to protecting the health and comfort of residents by controlling mosquitoes and reducing the transmission of mosquito-borne diseases.