tiny moths

Asked October 7, 2015, 12:59 PM EDT

Over the past few weeks we have been inundated with colonies of minuscule white moths {?} flying in random groups in ours and neighbors yards.... What are they? What if any significance?

Washington County Oregon

1 Response

Judging from your description of “colonies of minuscule white moths {?} flying in random groups,” the insects are most likely ash whiteflies, Siphoninus phillyreae, which were first identified in Oregon during 2014. Judging from the number of calls and emails we’ve been receiving from the public, it’s obvious the whiteflies have expanded their territory this year most likely due to the elevated temperatures during the winter and this summer. In other areas, these whiteflies have been potentially serious pests of ash trees and certain other woody plants but, in those areas, were soon brought under control after natural enemies were introduced.

Very little is known at this time about their potential significance ash whitefly might be in Oregon or what sort of management may be needed. Treatment, if any, should only be applied to the undersides of infested leaves because the most susceptible targets are the small oval youngsters.

This webpage (late 2015) for commercial growers has some background information and images of infested leaves: http://oregonstate.edu/dept/nurspest/Ash_whitefly.html. The entomologist has include a link to a local radio show on which she was interviewed about the whiteflies.

Also see this recent news report: http://www.kptv.com/Clip/11883316/those-little-white-bugs-ash-whitefly-numbers-growing-in-oregon