By Linda Weiford, WSU News

Richard Zack
Richard Zack

PULLMAN, Wash. – A force of nature has taken the sting out of the region’s wasp population.

“The number of yellow jackets is really down from what we normally see this time of summer — really down,” said Washington State University entomologist Richard Zack.

Wasps are typically a common sight – and nuisance – around gardens, picnics, hiking trails and garbage bins by mid-July, he said. This year, however, this sleek, black and yellow-striped insect is hardly noticeable.

Here’s why: Spring weather largely determines wasp population levels from year to year and this past one was not favorable to the insect’s survival, explained Zack.

“The extended cool, wet spring made it difficult for the emerging hibernating queens to forage for food and build nests. They probably suffered a high mortality rate,” he said.

Yellow jackets and paper wasps are the two most common types of wasps in Washington state.  March and April’s cool, damp spells struck a bigger blow to the yellow jacket populations.

“Of the lower number of paper wasps that are out there, they make up five out of every six wasps I’m seeing,” said Zack.

western yellow jacket photo
Western yellow jacket feeding on a honey bee. (Photo by Peter Landolt)

Because yellow jackets are more aggressive when threatened and inflict a more painful sting than the smaller-sized paper variety, this should come as good news to people who spend time outdoors.

Unlike bumble bees that feed on flowers and pollen, wasps consume insects and everything from spilled soda to barbequed ribs. And where bees sting only once and die, wasps can deliver multiple stings when defending themselves or their nests.

Nests still a nasty nuisance, threat

Even with the overall number of wasps significantly decreased, humans shouldn’t let down their collective guard, Zack cautions. A nest is still home to lots of workers and they’re busy searching for food, he said.

And those numbers will increase as we get deeper into summer, as colonies — originating with a single, surviving queen — reach their maximum size, said Peter Landolt, research entomologist with the U.S. Department of Agriculture in Yakima and WSU adjunct faculty member.

With a run of hot weather expected in August, “each nest has the potential to grow to the size of a basketball and produce a couple of thousand wasps,” he said.

To learn about the nests, stings and behaviors of Washington’s yellow jackets and paper wasps, read this publication by WSU’s Cooperative Extension:

https://ehs.wsu.edu/PH/pdfs/Yellowjackets%20and%20Paper%20Wasps.pdf