The Alameda County Mosquito Abatement District has found four additional Aedes aegypti mosquitoes in Pleasanton after announcing last week a new discovery of the non-native insect that hadn’t been seen in the county for a decade and is capable of spreading diseases.

The district placed traps in areas south of the Amador Valley neighborhood of Pleasanton and found mosquitoes inside and near the Alameda County Fairgrounds and neighborhoods northeast of the fairgrounds.

An Aedes aegypti mosquito was previously discovered last week in an area west of Amador Valley High School and east of Hopyard Road, the first time since 2014 that the species was detected in Alameda County. The Aedes aegypti mosquito can spread diseases like dengue, Zika and yellow fever, according to the district.

Mosquito district staff are going to all properties in the area to inspect for mosquitoes, which lay their eggs near water, and estimated they have inspected about a quarter of the properties in the initial detection area.

“The Alameda County Mosquito Abatement District appreciates the help of residents who allowed inspections on their property,” district general manager Ryan Clausnitzer said in a statement Tuesday. “Staff have been in the area conducting inspections over the weekend, and will continue to inspect properties over the next few weeks.”

A map show the area in Pleasanton affected by the invasive Aedes aegypti mosquito, requiring searches of all properties in the red zone by Alameda County Mosquito Abatement District staff. (Alameda County Mosquito Abatement District via Bay City News)

Staff members doing the inspections will be in uniforms with a logo on their shirts and will have additional identification if requested. The district said it is also working with fairgrounds staff to enhance monitoring and treatment for mosquitoes at that site.

Aedes aegypti is present in 19 counties throughout the state, including neighboring Contra Costa and Santa Clara counties.

More information on the district and its programs can be found on its website at https://www.mosquitoes.org.

Dan McMenamin is the managing editor at Bay City News, directing daily news coverage of the 12-county greater Bay Area. He has worked for BCN since 2008 and has been managing editor since 2014 after previously serving as BCN’s San Francisco bureau reporter. A UC Davis graduate, he came to BCN after working for a newspaper and nonprofit in the Davis area. He handles staffing, including coaching of our interns, day-to-day coverage decisions and management of the newswire.