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It's not absolutely clear why, but yellowjackets seem to be less active this summer

I live in East Medford and usually am surrounded with yellowjackets this time of year, but they are not here this year — what happened?

 — Jimmy G., Medford

Well Jimmy, this could go under the category: You've escaped those mean little critters thus far, but September is coming. 

No month gets under a yellowjacket's skin quite like September. 

"That's when their nests are maxed out and they begin foraging like crazy," Rick Hilton, an entomologist at the Oregon State University Experiment Station, told us.

That said, there are a variety of anecdotal threads contributing to the general decline of yellowjacket activity, the nasty little creatures that burrow into the ground then attack in droves when you least expect while you're hiking or playing in the yard.

Although he doesn't track actual populations, Hilton suggested a couple of scenarios have come into play. One thought is that last December's coldsnap, which produced sub-freezing temperatures here and there around the valley, played a key role. The second, which throws support for greater as well as less activity, is the drier-than-normal year.

Hilton said queens often winter in ground cavities such as old rodent borrows before emerging the following spring. How cold is cold enough to lessen the population remains debatable.

Secondly, drought drives yellowjackets to seek water. It's doubtful, however, all those nests have migrated to lakes and rivers.The data, on that one, Hilton said, is inconclusive.

The ground squirrel population has "gone nuts," Hilton said, perhaps making it harder for yellowjackets to find suitable winter quarters. "Although it's speculative, the cold snap in December is as good of an explanation as I can find."

Send questions to “Since You Asked,” Mail Tribune Newsroom, P.O. Box 1108, Medford, OR 97501; by fax to 541-776-4376; or by email to youasked@mailtribune.com. We’re sorry, but the volume of questions received prevents us from answering all of them.