I scratched my head over many years on this one. In interior Alaska, some summers were fantastically high yellowjacket years, other years you'd never see one. Why? Well, I was snap-trapping voles for many years, trying to get a handle on owl and marten food. I noticed a crash in voles led to the next summer being a banner yellowjacket year. The vole crashes (mostly red-backed voles) coincided with chinooks (warm February or March winds). I surmised that the voles would get wet during these chinooks, and when sub-freezing temperatures returned (which they always did), the voles succumbed to the elements.There were wild swings in the vole population, dropping or rising 40 times from year to year. I further looked at yellowjacket "cycles". On years that we had drastic chinooks and the vole populations crashed, we would have tremendous summer populations of yellowjackets and bald-faced hornets. It all made sense, when you considered that the voles, all winter long, are sub-nivean (beneath the snow) in the leaf litter and duff, eating over-wintering yellowjackets. With no voles around, many more overwintering yellowjackets survive to produce the eggs and the yellowjacket populations increase. It all made perfect sense.


Yellowjacket nests were most-often in trees.



Some nests were on rock cliffs, while some were ground-nests.



Red-backed voles were typical over-wintering yellowjacket predators.



I snap-trapped thousands of voles to monitor populations levels of marten prey.

that is very interesting, Jack!

Thank you for sharing your hard-won (and very thoughtful!) insights!

[I've suddenly become a big Vole fan!]

white marlin - I, too, am a big vole fan. There's about 6 species that are very important prey items for the marten in Alaska, foremost of which is the red-backed vole. It's what's for dinner!

Jack

Hi Jack -- Thanks for the insights. Quite interesting. Your hypothesis, I think, presumes that a pretty significant % of yellowjackets spend their winters on the ground in AK? They have both abve and in ground nests here in IN; but we notice more in trees, especially after leaf drop in the fall. they're a PITA to me, as every few years, they get into the soffit cracks and build a nest inside the house rafters. Plus, they're constant nuisance as they and the bald face's chew the wood on the kids' playset in late summer/early fall and it keeps the kids from playing on the swings/slides. I've since learned, from the smart folks on this forum, how to get rid of the nests using canned chicken + Navigator SC: https://trapperman.com/forum/ubbthreads.php/topics/7867219/yellow-jackets#Post7867219

UGH..... if I could blink and make things disappear....those and Baldies. They kill honeybees. My favorite insect.

They are well programmed in how they take wood and make nests. I'll give them that.

Thank you, Jack , I too love voles !

I feel the same way. A couple of years ago , there was a honeybee in the place I work. It was buzzing around the windows to get out.
My co-worker thought I was nuts because I very carefully caught it alive with a cup and a piece of paper , then took it outside. If it was a yellow jacket it would have been dead.




Great write-up , Jack. Kudos.

People are sometimes not aware that yellowjackets produce viable queens that are the ones that overwinter and keep the species going. All the workers die out late each year.

I like your hypothesis Jack. It must be very satisfying to se put the pieces of the puzzle together like that.

Very interesting..."here", I've never seen an above ground yellow jacket nest, all are under ground, The hornets build those paper nests in trees and shrubs...

I always thought the big hanging nests were paper wasps. I don't think I have ever seen a bald faced hornet nest, we don't have a large population of them. I have found I can mostly eliminate yellow jackets by heavily trapping the queens when they appear in the spring, a wet spring seems to affect them also.
I always enjoy your posts Jack.

Jack , studies on Wis martens found the red back vole to be a preferred lunch if available. Studies show areas of high population of red back voles in marten territores carry martens

The paper nesting and ground nesting yellowjackets are different species.

My experience as well. Ground nests for yellow jackets here. The paper nests are bald faced hornets and the yellow European hornets nest in hollow trees.

Interesting since hornets and wasps make themselves known i've noticed in wet years hanging nests Dry years ground nests by both jackets and baldies And after a mild winter like we are having now an uptick in bugs of all kinds specifically ticks wasps and hornets

I always thought that yellow jackets lived in the ground and those large paper nests were bald faced hornets. In any event I like to see all of the red back voles dead.

Very interesting, Jeff. I'll be watching this closely. We had an "average" summer in 2023 (12 inches annually). Yellowjackets were way down. We've had several "dry" years before that (2018-2022) and yellowjackets much more common.

We've always had lots of wasps on dry years. Flea man should chime in soon.
We were cutting a trail last summer. buddy drops his axe and runs towards the quad and takes a knee. I'm thinking "you lazy bugger get back to chopping" as I'm running the saw and 30 yards away. He disturbed a nest under a log, got hit about a dozen times and couldn't see for a minute or 2. Looked like he got hit with a baseball bat across his rearend. Usually they come for me and I'll bolt for about 1/4 mile, I HATE those things!

In interior Alaska, both Vespula and Dolichovespula seem to prefer aerial paper nests. I've never seen a bald-faced hornet (Dolichovespula) nest in the ground. but plenty of yellowjackets (Vespula). Most common yellowjacket is probably V. norvegicus.

Down here our "ground nesting" yellow jackets aren't always in the ground. They regularly take up in above ground cavities. No open air nests like hornets though.

One interesting and painful twist is they don't always die out overwinter. In mild winters you can have a nest survive and when that happens you end up with multiple foundresses surviving and working cooperatively to build massive nests.

The largest I've ever removed I quit counting at eight foundresses and occupied a four foot diameter hole in a dirt bank.

One of my older brothers worked for Massachussets Parks and Recreation for a summer on their yellowjacket eradication team. Of all the baits tunafish was by far the best. The oilier the better.

that's been my experience in Pennsylvania.