A topic that I've considered posting over the last couple of years involves the fairly recent establishment of a non-native wasp to the Pacific Northwest. This is a European wasp called Polistes dominula. Because this post is rather spur-of-the-moment, on a whim, I haven't looked up all the specifics and dates, but those interested can do so by googling, no doubt.
My wife and I moved from southern California to our new house/parcel in about June 1999. I think that it was roughly about that time or shortly thereafter that a wasp, new to North America, was first found around the Port of Tacoma, WA, got established, and then began to systematically expand its range in the PNW. In about 2005, Polistes dominula first showed up on our property here in western Lewis County, WA, and in rather short order it had settled-in and was soon a common wasp. Thankfully, it's not an aggressive wasp species. It looks a little like our common yellow-jacket hornets, but has a thinner bauplan, yellow antennae, and doesn't sting you for no good gol-dang reason. Personally, I don't like non-native, invasive species of any sort coming into "my" area, but these wasps were reasonably well-mannered and weren't much of a bother.
In 2015, while wandering daily amid my recently grafted apples and pears, I became profoundly impressed as I watched these wasps -- along with our wonderful native jumping spiders (Salticidae) -- as they regularly patrolled the plants and consumed and controlled caterpillars and other pests of various sorts. They were incredibly efficient in this task and I began to feel an appreciation for them.
Then came the spring of 2016 (--last year). My wife and I continually observed that whenever the overwintered queens emerged, they were engaged in battles with other queens of the same species. When we'd see a queen she was almost invariably tangled with another in a literal fight to the death. The population of Polistes dominula last year plummeted to almost zero. Throughout the growing season I rarely saw a Polistes, and the number of destructive caterpillars that I had to find and kill myself rose amazingly. Fortunately, our salticids were still present and on the job, but the near absence of the Polistes wasps was notable.
This past year (2017) the number of Polistes began to rise again, slowly, and I did note that there were fewer caterpillars for me to find, identify, and feed to a chicken or stomp on; however, the value of the wasps as "helpful" gleaners was notable.
My theory is that the original Polistes population which settled our property all originated from one queen, and those that appeared and engaged in warfare with our original, established population had originated from another queen whose progeny had only just arrived in our area. Apparently there are such cases of inter-lineal warfare recorded among ants. I've never said this about a non-native invasive species before (--and probably never will again--), but I'm rather hoping that our Polistes species rebuilds to its previous level as they were such a boon to pest control.
For those of you in the PNW who are aware of the Polistes dominula introduction (--accidental, apparently--) and have them in your orchard or garden, I'm quite curious as to what your observations and experiences with them may have been. Presumably they're here to stay -- just like the lawn dandelions. Any time a "new" species or organism enters an ecosystem, there is a transitional period while changes occur that will result in a "re-balanced" ecosystem. [This can take decades, centuries, or even millennia.] Obviously it's difficult to gauge the effects of individual introductions to our ecosystems given how profoundly humans have altered our landscape, but all observations can potentially be informative.
Any comments or observations on the Polistes? I'm a naturalist, an observer of the natural world, and inquisitive, and have been ever since I was a little tyke in southern Brazil. Any relevant observations would be appreciated.
Reinettes
Excellents observations and information! New to the Blue Ridge Plateau of SW Virginia, I’ve assumed the wasps you’ve described were simply another unusual ‘Eastern Species’ of something this PNW native had never seen. Now, they make sense.
It appears Polistes dominula has established itself in numerous eastern US states but is a newer arrival out west. The description I (just) read attributes their increase in numbers over our domestic wasps to their ‘earlier nest building’ and increased likelihood to use man made structures and household shelters, including the use of their previous season's nests. But this ‘first out & active’ behavior is also attributing to their higher mortality due to late Spring freezes…
In Oregon, I loved ‘my wasps,’ and appeared to have designed my home’s oversized rain-shedding eaves for their accommodation 
We’d monitor with appreciation their yearly addition of nests, noticing they did appear to ‘reuse’ previous ones, and we'd only show concern for nests directly above an exit door, removing those at an early stage. Other than the occasional ‘teenage wasp’ dropping on or near as we’d use the decks, encounters resulting in stings were rare.
And in the orchard - they were obviously on my side 
While living in OR, around 2 years ago, I can’t say that I was aware of these newcomers ... also called European Paper Wasps or, Social Wasps. But, I’d likely have assumed they were simply immature natives (or ‘teenagers’), thus a bit smaller. And since I’d never considered the larger, long-segmented native wasps to be aggressive (unlike their assumed cousins, the Yellow Jackets), I likely admired and encouraged both...
That said, only weeks ago I needed to access a storage area above my carport here in SW VA. Unfortunately, there were two active nests of the Paper Wasps (newcomers) fastened to the panel. With my ladder up and quite close, they never bothered me … as I sadly exterminated them... They were definitely the ‘newer wasps,’ and not the ‘big ol’ yellow one’s’ I'd known from childhood out west.
However, they have full access to the underside of said carport, with my encouragement to proliferate ... just not on my only attic access (a daughter was visiting and I needed to carve out some additional interior space, or I’d have happily left them).. For days a few stragglers were searching for their nests ... but never once did they become aggressive or a nuisance.
Now, if they could be encouraged to bore into my lawn in order to carve up & carry off the fat white larvae of the Japanese Beetles ..that do so well around here -- I’d jump for joy 
-- Hey - Regularly I read posts ‘here’ that appear worthy of our HOS Pome News publication. A Life Member of the HOS, I’ve chosen not to receive the News since moving, so am not sure what’s been submitted... But I’d encourage our regular contributors here to consider and perhaps submit their longer more researched pieces to its editor. Obviously, a one-sided conversation in comparison to here, but enough to spark some interest and personal investigation in orchard related subjects for our members ~
Viron,
Thanks for your very interesting response. I had not been aware that the Polistes dominula had also settled into any of the eastern U.S. states; it was a surprise to "hear" you say that they're there on the Blue Ridge Plateau! I don't know its natural distribution in Europe, but given that they've co-habitated with humans of various sorts in Europe for many millennia across a broad range of ecological and climatic zones, I'm guessing that the species could establish itself very widely here in North America.
"....I (just) read attributes their increase in numbers over our domestic wasps to their ‘earlier nest building’ and increased likelihood to use man made structures and household shelters, including the use of their previous season's nests. But this ‘first out & active’ behavior is also attributing to their higher mortality due to late Spring freezes… "
'Tis indeed true that these buggers emerge early to establish their nests! Despite my appreciation for the role they're serving in critter control, I've been concomitantly frustrated by the fact that the queens aren't averse to starting a comb inside of one of the Violet Green Swallow houses that I've made. Our VG Swallows generally arrive within the first week of April but, when they're checking-out the houses, if they find that a Polistes has already begun a "comb" within they'll reject it as an option. It makes the timing of putting up the swallow houses critically narrow, and a summer without VGS's nesting here and bringing their joyful presence and incredible aerobatics is a real bummer for me. ...And yes, the Polistes dominula definitely love the under-eaves of virtually any building.
"... also called European Paper Wasps or, Social Wasps...."
[As an aside, I rather avoided the use of a "common name" in my posting so that anyone reading and interested would be able to look-up the particular species without confusion. This carries over from my general interest in the natural sciences where I''ll be reading an article of interest and then only a "common name" is used. Being unfamiliar with the common name, I look it up only to find that it can apply to more than one species -- sometimes even to an organism in a different genus or family of organisms! I learned about Latin binomials when I was a little kid growing up with a set of World Book Encyclopedias, so I tend to use them when I can for lack of ambiguity when I'm writing (--unless it's something like "apple" 
[Malus domestica], which every reader should understand). I always feel a bit bad about it lest someone think I'm being pretentious when I only want to be unambiguous. I'm not really used to writing for a more general readership.]
"...[O]nly weeks ago I needed to access a storage area above my carport here in SW VA. Unfortunately, there were two active nests of the Paper Wasps (newcomers) fastened to the panel. With my ladder up and quite close, they never bothered me … as I sadly exterminated them.... ...For days a few stragglers were searching for their nests ... but never once did they become aggressive or a nuisance."
Yes, that definitely sounds like them. If I have to remove one of their nests because it's "in the way," I'll try to get them out of the way and then flick it off to the ground or sometimes just pull it off. Generally, I'll put it on the ground quite some distance away and grind it into the ground. Nevertheless, those wasps that were on it will remain in the area, constantly flying back to the site of the nest for days.... Somehow, I always feel a bit bad about it.
"...Now, if they could be encouraged to bore into my lawn in order to carve up & carry off the fat white larvae of the Japanese Beetles ..that do so well around here -- I’d jump for joy "
Amen! Thank God we don't have Japanese beetles here, but some years ago I went back to Indiana to visit my sister and brother-in-law and there were Japanese Beetles everywhere! I explored around and it seemed that those infernal beetles were capable of doing damage to virtually every plant family that was represented. Now that's a plague!
Reinettes
Reneittes: If your swallow houses that have wasps are detracting swallows then wouldn't having hornets nests in apple trees detract codling moth from roosting there?
The reason I use "hornets" is that the nests are so huge and easily (with great caution) be used to suck a large quantity using a vacuum. Such an event took place many years ago at my ex-inlaws place where researchers had used them as experimental venoms. In the vacuum canister they were cooled and caused to hibernate.
If successful such a strategy would have to be invoked during codling moth flights to keep the scent of crushing hornets fresh.
Then again people know me about my pro-active curiousity as well.
Rooney said:
"If your swallow houses that have wasps are detracting swallows then wouldn't having hornets nests in apple trees detract codling moth from roosting there?"
Rooney -- I wasn't quite sure what to make of your posting 
. The Polistes get established so early in the season that the yellow jackets and the bald-faced hornets that are native here are basically "not even out of the starting gate." And the Codling Moths (Cydia pomonella) are flying and doing their dirty deeds quite some time before our yellow jackets or bald-faced hornets have really had a chance to build up their population sizes. Our yellow jackets build up steadily over the summer, but --at least on our parcel-- I generally don't start seeing bald-faced hornets until later in the summer, and even then they're few and far between. It's hard for me to imagine them being helpful early in the season for Codling Moth control, at least here where I am. Besides, those malevolent-looking Bald-faced hornets intimidate me more than "our" Yellow Jackets, who have stung me unprovoked on more than one occasion. I can't imagine trying to foster hornets in the orchard if they're not there at the proper time of year to do the job on Codling moths.... But, I say, if it works for you in your situation then go for it!
John S. said:
"Many people use carrot family umbelliferae vegetables to attract parasitoid wasps...."
John -- I've read that somewhere as well. Umbellifers (Apiaceae) may have small flowers, but they're very important for a broad diversity of insect species. It's a slow process for me as I try to increase the diversity of plants for birds and insects on our property, but I'm in the midst of --year-by-year-- trying to add more diversity in the Umbelliferae and the Labiatae (Lamiaceae, mint family). The greater the diversity of food-plants, and especially habitats and microhabitats, the greater the diversity of insects that can find a place to establish and reproduce. I really want to promote our native bee species in the coming years, many of which are ground-nesting species. Diversity in habitats and plants is very important in the landscape.
--Reinettes
I hope most of us were able to see that what I asked was not really a question at all, but rather could see me as a loop to a comment that would lead the reader into the thinking minds of what controls swallows might control codling moth as a biological control. To clarify I think I have to say (what I thought I conveyed before), is I believe pests such as codling moths "will" become detracted from "breeding" in any home-owner's fruit tree as long as the pest can catch the sense "instinctively" there is something wrong... In itself to say we can only see (try it) to take dormant caught wasps of any kind and crush them, then place them in fruit trees.
I have not done so but I will risk doing it some day once I find some equipment and source of big of hornets or wasps nests. If not them maybe the idea will stir the mind of those put in charge of supplying the fruit industry with new ideas. If the above works then potentially it may draw chemists into the picture of what traces or signatures the crushed bodies of predators are giving themselves away as.
Reinettes-remember that many species of these types of plants don't need any care to thrive. If you have a vacant lot, Queen anne's lace just shows up. I planted skirret, a chinese umbelliferae vegetable and it's all you can eat, and no work. Same with Earth Chestnut and most mint relatives. In fact, invasiveness may be a more pertinent question than work required to make them grow.
John S
PDX OR
Hi, Rooney -- My sincere apologies for misunderstanding your earlier post. If you're talking about crushed wasps or their hives and the pheromones that would likely be associated with them as a way of dissuading Codling moths, then you may very well be on to a great idea. We modern "domesticated humans" have lost our original sensitivities to the natural world that can still be found in the few remaining hunter-gatherer societies. Even at that level, though, we humans still weren't privy to the extreme subtleties of pheromones and other chemical communications in use by "lower life forms." It's only been in recent years, for example, that bacteria have been found to communicate with each other via chemicals. The more we know, the more we know just how little we actually know.
John S. -- While wanting to increase the diversity of Labiatae & Umbelliferae on our property, I am always concerned about avoiding any that might be unduly invasive. When we bought our place some 17-18 years ago, the previous owners had planted Lemon Balm (Melissa officinalis) on the north side of the house. I've left them because our bumblebees really love them, but in the intervening years I've noticed them gradually invading beyond their original area. I'll have to do some strategic weeding this year. I have some Earth Chestnut (Bunium bulbocastanum) in pots and really like them. The delicate foliage is very attractive, although the small root tubers would be difficult to make a meal of. This winter I hope to start seeds of Mellitis melissophyllum (from Europe) which should attract bees, and our native Cow Parsnip (Heracleum sphondyleum, or whatever the taxonomists are calling it this year) which should be good for the diversity of little insects who like umbellifer flowers. Of course, in the vegetable garden there are usually carrots, dill, parsley, chinese celery, and such, but I like to have a balance of both cultivated and native.
Reinettes
It's kind of funny only for the few seers (as few as we are) that the developers, as far as the people who make pesticides, are errant to realize that it's way too late when eggs are laid. These codling moths for example, can be fixed with far greater efficacy as adults than can after hundreds of eggs laid by a female. Statistically our night flying bats have been able to show us just how good the results are.
The only bat crutch would be how one would attract bats. So bats should be our number one teachers that point that wasp or bee pheromones seeking makes sense. In turn, to vacate a wasp nest, and place one in an earwig infested tree (having seen a few in my yard) at night. If there earwigs had found cover there then investigate live wasp nests. Eventually finding where, by process the insective deterrent originates.
I added bee into the mix above because I used to tend honeybees in a glass observation hive. I also studied them in great detail as a teenager. They emit wax and propolis that deter bacteria and other things as well.
Update: I just found they have officially researched bats and what they eat on west coast.
Great article Rooney!
I would like to put up bat houses. I have varied heights in my orchard, I'm organic, and I have a variety of species. I am excited about them eating cabbage moth and codling moth. The only impediment I see is I have no creek or long runway of continuous water. i'm going to have to think about how that could be possible.
John S
PDX OR
Ah, bats! Beloved bats!
For several years I've been wanting to set-up a bat house on our property to encourage them and provide a safe abode while they're here in the summertime. There's no doubt that bats are truly beneficial in the overall ecological network. "Stand aside Robin! A Bat is required for the job!" I have a book on bats that should give me the identity of which species (--or possibly species, plural--) occur here. However, not being a chiropterologist, I have made no attempt with a mist net or otherwise to capture one. I'm just pleased to know that they come back each summer.
Sadly, my wife is like so many people in the general populace whose minds have been tainted by all the life-long hype about rabies and vampire bats (and maybe even vampires?). Bats have been so terribly and unfairly maligned. When the weather finally starts mellowing in early summer here, I like to search the sky at dusk hoping to see our first bat of the season... just to know that they're back. My wife refuses to have a bat house on the property, but (--as we're both hard-headedly obstinate--) this is one difference of opinion where there will ultimately be one bat house or more. The Newaukum River runs a bit less than a half-mile north of us, which might be a bit too far for bats on our property, and bats really like skimming over the water for insects. I'm hoping to make at least one -- and preferably two or three -- ponds on our property in the not-too-distant future. At least one of them should be of good size. This wouldn't just be for the bats, but also because I love to cultivate wetland plants, whether the particular plant species like seeps, or pond margins, or are submerged or aquatic emergents. Pond and wetland life have fascinated me ever since I was a kid.
It's really all about diversity. Diversity of habitats, soils or substrates, plants, etc. If the natural diversity of a sufficiently large area is preserved, promoted, and worked toward, the diversity of insects, birds, and other wildlife naturally associated with those habitats will be drawn to it. And if you have a balance of the flora and fauna that are naturally native to the area, then an equilibrium will develop which will not necessarily be what the human most wants, but will be what the countless other species balance out to... and in the absence of anthropogenic toxic chemicals, there will generally be a reasonable result.
Reinettes.
Love your take on bats, Reinettes. I think you’ve got ‘Big & Little Brown’ bats around there. Not very creative names, but not too difficult to tell apart. I’d belonged to Bat Conservation International (BCI) too…
Miss ‘my bats’... I had around 20 houses set up for them at one time, 3 were innovative ‘brood nests,’ with fine screens inside for the ‘pups’ to cling to. Can’t say I’d ever noticed any activity in them … but found my setting of a mature mixed forest provided all the habitat they needed.
And ponds, yes! A favorite memory is, not only watching 17 bats emerge from a rotted Alder trunk while sitting in my boat on the pond ... but watching bats circle overhead while taking turns skimming the water alongside the boat to drink… And in 33 years of close proximity, with a bat inside the house, woodstove or garage ever so often … no bites or Vampires ...just a periodically freaked out wife and a couple of squealing daughters
Good Morning All,
I finally remembered to check into the Forum this morning, and lo and behold, saw this fascinating thread. A comment made early on by Viron is absolutely correct; an anecdotal article on non-native wasps in the orchard would be worthy of the Pome News. I am the HOS editor for the quarterly newsletter and would welcome working with any of you who would be willing to participate in such an article. I'm currently soliciting material for the Spring issue. We would have about 2 months to put an article together. I could get the ball rolling by consolidating information from this thread into a "draft" to use as a starting point. Do I have enough interested parties to participate as info contributors/gatherers, reviewers, and proofreaders? Please let me know.
I would also welcome articles/material on other appropriate subjects for the Pome News newsletter. We're moving into spring. What information would benefit our members most for this season?
bucolic
(Theresa Homolac)
Idyllwild
simplepress
jafar
Marsha H
Viron
John S
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