This photo offers a contrast to an earlier post, Just A Photo: A Table for Eight Please? I was visiting Twentymile Creek in southeastern Oregon last year and there were loads of these Sooty Dancers (Argia lugens) ovipositing in tandem on floating leaf debris. It appears that each female is inserting eggs into the underside of the leaves by curving the abdomen up. Unlike the more civilized four pairs of Vivid Dancers (A. vivida) in that earlier post, these four couples are all over the place and all over each other. It takes a little effort to figure out which male is in tandem with which female!
Just as in that earlier post, this is a case of contact guarding—each male remains attached to the female while she oviposits in order to prevent other males from copulating with her and removing or displacing his sperm. This ensures that the eggs she is depositing at the moment were fertilized by him.