Nice captures.
Looks like that might be it. I checked here: http://bugguide.net/node/view/554
I don't know about vespula germanica specifically, but many wasps in that genus are not non-aggressive. If they perceive a threat, they will sting readily, and if you threaten a nest (for example, by accidentally stepping on a nest in the ground), they will swarm and sting.
I give wasps distance. Been hit too many times.
Nice shots
As I found when one, un noticed, was doing the breast stroke in my glass of beer. It stung me on the tongue. Thankfully I didn't have a reaction and I've become very cautious since.
But on to the real subject. Beautifully sharp but little more DOF next time if poss. Joanne. None the less three nice shots.
I think the problem is more the focus point, not DOF. The focus point seems to be in front of the bug in all three photos, particularly the first two. The in-focus region captures some of the bug. This is clearest in the second image, in which the leg extended toward the camera is almost entirely in focus, while half the head, the hairs on the back, and the abdomen aren't.
To avoid this, I try to focus on the near eye and keep the bug as close to parallel to the sensor as possible. Even with that and an aperture of f/13, you often can't get an entire large bug in focus without stacking (which I have never successfully done with bugs). So, the goal is to keep what people most focus on, in particular, the head, in sharp focus.
Very good captures of a group that I loathe !
I agree with Dan about the focus, and also I suspect that all the images (but particularly 1 and 3) have been over-sharpened during processing.
Cheers.
Philip