Every summer paper wasps nest around the outside of the house. These in the photos are on the porch ceiling (so actually they are clinging UPSIDE DOWN, I rotated the photos to make them easier to comprehend). The nests are attended by multiple individuals but they seem to be pretty goodnatured, never bothering me or the dogs, even if I get fairly close to photograph them on the nest. At this point in the year the females are just exploring to find where to build a nest.
This is the first time I have noticed the activity shown, where one wasp gets on top of another. The one on the bottom has her wings folded over her body making the body look dark from some angles so at first I thought this was a predatory behavior between two species.
In the preceding picture the wasp that will be "mounted" adopts a submissive posture while two others "stand up" to do something: recognize each other? Then one gets on top of the submissive one, and the third one hangs around or wanders off. Often there is no third wasp, just the "dominant" and "submissive" ones.
Female paper wasps collaborate on building and guarding a nest though only one female may actually lay eggs in the nest. I don't think the males appear at the nest site, but breeding takes place before nestbuilding, elsewhere. So I'm thinking this isn't copulation. Maybe one female exerting dominance to become the one that reproduces? I need to mark them so I could track better.
More details: they build small (2-4 inches across) cup-shaped nests attached to a ceiling or inside a sheltered place like a shade, with a slender pedicel, and each nest contains >15 cells. Cells are stopped up with more paper not with the cobwebby material I have seen in pictures of the nests of some species.
I would be grateful for more information on these very interesting insects. Although observed in SW Oregon they may be European paper wasps but I'm not sure.