Suspected bomb in Atherton was a mosquito monitoring device

Middlefield Road in Atherton was closed Wednesday afternoon, Aug. 14, due to a report of a suspicious device suspected of being a bomb. That device turned out to be a mosquito monitoring device placed in the vicinity by the San Mateo County Vector and Mosquito Control District, said Atherton Police Chief Steve McCulley.

It is likely that the mosquito monitoring device was placed in the vicinity due to the detection of West Nile virus in a dead bird from Atherton. Data from the California Department of Public Health’s Vector-Borne Disease section shows that the dead bird was found about a block away from where the closure for the suspicious device took place. 

“​​In response to finding West Nile virus, we do an extra check of all potential mosquito breeding sources in the immediate area,” said Rachel Curtis-Robles, San Mateo County Vector Control District’s public health education and outreach officer. “We also set extra mosquito surveillance traps in the days after the initial finding.  The mosquitoes in those traps are tested for West Nile virus.”

Curtis-Robles explained that the traps are designed by the Vector Control district to attract mosquitos to collect for testing.

“We use mosquito traps in our everyday work for detecting mosquitoes … they have a cooler holding dry ice (carbon dioxide) to attract mosquitoes, and they have a small, battery-powered fan to pull mosquitoes into a mesh bag, where they are held until our staff collect the trap the next day,” she said. “Traps are typically set in the afternoon and collected the following morning.”

She also said that the Vector Control district is currently making sure to provide extra information about the traps throughout their networks.

“The traps are all labeled with our logo and contact information,” said Curtis-Robles. “People can always call with any questions. Every few years we receive a call about one of our traps, but it is very infrequent that they receive attention from the public.”

McCulley said in an email to this news organization that the Atherton Police Department was first alerted to the presence of the device by a person who was walking on the street. 

San Mateo County Sheriff’s officers and what appeared to be a county bomb squad truck appeared on the scene around 1:30 p.m.

“It was reported as a possible suspicious device,” McCulley said on Wednesday afternoon, Aug. 14. “We are having the bomb squad respond as a precaution.”

The road closure began around 12:30 p.m. on Wednesday, Aug. 14, and was back open by 2:20 p.m., according to a town news alert.

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