Asked September 29, 2015, 3:04 PM EDT
Washington County Oregon
Many people in our nearby counties have noticed clouds of the same speck-sized flying insects during the past several weeks. They were recently identified as ash whiteflies, Siphoninus phillyreae, potentially serious pests of ash trees and certain other woody plants. These insects were first reported as a somewhat limited population in the Willamette Valley during 2014. But from the calls and emails we’ve been receiving from the public, it’s obvious the whiteflies have expanded their territory this year.
Very little is known at this time about how damaging ash whitefly will be in our region or what sort of management may be needed. This new webpage (late 2015) for commercial growers has some background information and images of infested leaves: http://oregonstate.edu/dept/nurspest/Ash_whitefly.html. Treatment, if needed, should only be applied if infested leaves are found.