Sunday, October 24, 2010

Aculeata Agnoistes: The Prairie Yellowjacket Vespula atropilosa

In general, I try to adorn this blog with as many of my wife’s pictures as possible. After all, she is the photographer (and the one with the cumbersome and expensive camera gear). I’m strictly the put-a-name-on-the-bug person. And when it comes to cameras, I’m strictly a point-and-shoot person. As a result, I rarely come up with an insect picture that is of much use. This isn’t entirely the camera’s fault – people like Terry Thormin and an earlier Ted MacRae (who has now moved on to a real camera and even more spectacular photos) have produced numerous great insect photos with point-and-shoots (and Alex Wild can even produce good pictures with a cell phone) – but for anything that isn’t large and slow-moving, putting me and a point-and-shoot (originally a CoolPix 5700 and now a Lumix DMC-FZ28) after them is mostly a lesson in humility. To me the worst affliction of point-and-shoot insect photography is the interminable delay between pressing the button and the camera snapping the picture.
In this case, a colony of the Prairie Yellowjacket Vespula atropilosa under the steps in the garden in front of Government House, my wife was not around and I had to be the photographer. I won’t share the two dozen beautifully focused pictures of the wasp-less steps with you. Still, with enough persistence and cooperative bugs, even I can acquire images adequate to document the identity of an insect. Usually I would use the Identification Atlas of the Vespidae (Hymenoptera, Aculeata) of the northeastern Nearctic region to identify a yellowjacket. However, as is true of so much of Canadian life, the Atlas only works for species in the East. The Prairie Yellowjacket is a western species and reaches its northeastern distributional limit in Edmonton: it isn’t in the key.
If you used the Atlas more or less correctly, you should end up in the rufa species-group before your started to founder. The two yellow spots on top the first abdominal segment are helpful – if mostly fused to the posterior yellow band. If you made some wrong choices, you might end up in the vulgaris species-group and start to feel like I do when using my point-shoot to take a picture of an insect. When the characters on your insect and those in the key start to diverge widely, it is usually a sign that somewhere you have made a wrong choice.
Learning the true name of a yellowjacket may seem like a bit of an egghead thing, but if you were trying to decide if you needed to eliminate the nest, it could be quite useful. In general, rufa group yellowjackets mind their own business and spend their time hunting insects to feed their brood. That means you could consider them useful ‘natural enemies’. If you stir up the nest, yes they will attack and sting you (so will bumblebees), but otherwise you might hardly notice them and probably most of what they eat wouldn’t be missed.

Vulgaris group species, however, will both hunt and scavenge and are quite willing to share whatever you are trying to eat or drink – and if you object, they are happy to sting you. They also have larger colonies and tend to be more aggressive. Every spring I eliminate any vulgaris group species trying to take up residence in my yard. This usually means the Western Yellojacket Vespula pensylvanica (it gets just east enough to be in the Atlas). I also take out the Baldfaced Hornets Dolichovespula maculata. In contrast to species of Vespula that tend to nest underground, Dolichovespula tend to nest in trees and shrubs (or on fences) where you are more likely to bump into them. The Baldfaced Hornet is the largest and most aggressive member of its genus and it pays to go after the nests when they are small.
Like other members of its hunting group, the Prairie Yellowjacket tends to nest underground and to have smaller nests than vulgaris group species – a few hundred rather than a few thousand workers. Unfortunately, although “restricted to the Canadian and Transition Zones of the Boreal Region”*, the Prairie Yellowjacket is also happy with the open areas we create such as golf courses and parks, so even if you mind your own business you may encounter this wasp. You can learn a fair amount about it – and even have a good chance of keying it out correctly – if you consult Akre et al. (1981)*, one of those great monographs that the USDA used to produce. You can also find most of the information and illustrations from this book on line at Discover Life. I suppose I might regret it, but if a Prairie Yellowjacket decided to nest under my steps, I think I’d let it.

*Akre, R.D., A. Greene, J.F. MacDonald, P.J. Landholt, and H.G. Davis. (1981). Yellowjackets of North America, North of Mexico. U.S. Department of Agriculture, Washington, D.C. Handbook #552.


  1. Your persistence paid off, great in-flight shot! And a nice find for this time of year.

    I'll bet that the pest control people don't bother to explain the niceties of wasp behaviour when they are called in to destroy nests. If it's yellow and stripey, it's all vulgaris to them.

    I allowed two bald faced hornets nests to persist on our property this year. One petered out after reaching only the size of a baseball. The other was in the clematis above the front entrance. This one reached the size of my head, but at no time did the wasps become a nuisance.I guess their flight path was high enough that it didn't conflict with our walk to the front door.

    Thanks for the link to Discover Life, that will be a useful site for future reference.

  2. I was using Lumix DMC when I started :)

    Great landing shot.

    I have always regarded the detection of a bald-faced hornet nest before it is destroyed by local bullies to be cause for celebration. Maybe tney're more numerous further north. I've collected several nests in the fall months (suitably treated to prevent things from suddenly coming alive indoors) that adorn both my home and real offices.

    Did I mention great landing shot?!

  3. Hi Adrian,

    You have better luck with maculata than I do - I find them annoying. I admit that their buzzing you in the face behaviour is interesting - most insects try to get away when you wave your hands at them. Also, D. maculata is a very efficient predator of flies visiting flowers. It is fascinating to watch.

    I would definitely take out any nest above my door, but would probably leave any nests high in trees (too hard to get to anyway). My rule is to try and avoid unpleasant encounters and enjoy my bug garden, so any nest likely to be disturbed goes. Bald-faced hornets are the most common worker hornets in my yard anyway - and along with some V. pensylvanica and germanica, just about the only hornets in the yard this cold and dreary summer. I saw queen yellowjackets at flowers well into July, so I suspect quite a few colonies failed.

  4. Hi Ted,

    I do like the Lumix: light, easy to handle, not too complicated, and just fine for flowers, landscapes, and an occasional lucky shot.

    When we first moved to Edmonton, we stayed at a house with several large cabinets that were used to make hornet nests. Apparently, this guy would collect queens in the spring, set them up in the cabinets, and then feed them 'prey' (possibly hamburger) and coloured paper. The resulting multicoloured football-sized nests were interesting in a whimsical way, sort of like the maggot paintings Alex Wild featured the other day.

  5. I remember seeing a newspaper article on those nests at some point...very cute!