Aerial insecticide spraying planned tonight for Tri-Cities mosquitoes

The Benton County Mosquito Control will be spraying the area around the Yakima River in Richland and West Richland with insecticide from 8 to 10 p.m. Tuesday, May 6.

The district is responding to high adult mosquito population numbers, it said in a social media post.

The spraying will extend from the Richland Wye near Bateman Island up the river through south Richland and a strip of land near the bypass highway through Richland. It will also cover from part of West Richland to just south of Wanawish Dam.

It takes up to 20 minutes for the chemical dropped from an airplane to drift to the ground, so people who see the plane flying overhead have time to go indoors.

The chemical used, Naled, breaks down within hours of application, reducing any long-term effects on the environment, according to the mosquito control district.

This story was originally published May 6, 2025 at 12:47 PM.