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Nightmare on Aphid Street – wooly white insects invade neighborhoods, parks

By Linda Weiford, WSU News  

A single aphidPULLMAN, Wash.Hovering masses of puffy gnat-like bugs have invaded the Inland Northwest, sticking to windshields, dive-bombing people’s eyes and getting into their mouths.

They’re called smoky-winged ash aphids and their massing has been spawned by warm autumn days, said entomologist Richard Zack of Washington State University.

“We’ve had some recent nice sunny, mild days this fall, which triggers the aphids to fly. They’re most active in the mid to late afternoon when it is warmest. Sometimes, they appear to be everywhere,” he said.

If possible, look beyond the annoyance factor and enjoy the aphid airshow. Once in flight, their fuzzy white posteriors pulse in mid-air. Consequently, the insects flit about like snowflakes on steroids refusing to fall.

Swarms of white, fuzzy aphids pulse the air in Moscow, Idaho, during a late-October afternoon. (Photos by Linda Weiford, WSU News)

“Many aphid species produce a wax-like substance that gives them a whitish color and wooly appearance when they fly, especially when backlit by the sun,” Zack explained.

After hosting on fir trees and other conifers during summer months, the females are making their autumn move to ash trees to lay eggs.

“Only the eggs will survive winter.  Everything we see flying around right now will die,” he said.

Expect the huge clouds of aphids to dissipate around Halloween as temperatures start to dip. In the meantime, keep in mind that the ample insect swarms are a nuisance, not a threat. While some aphids destroy vegetation, not the smoky-winged ash variety.

“They are of little to no economic importance to trees and plants. And no, they don’t suck blood,” said Zack.


Media contacts:

Richard Zack, WSU entomologist, 509-335-7247,

Linda Weiford, WSU News, 509-335-7209,

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