The wasps habitually flicked their wings when away from the group. Within the group, they seldom flicked their wings. I fished one drowning out of the birdbath and when he flew back to the window ledge, the others surrounded him, touching him with their feet and antennae. This went on for two hours, until the near-victim flicked his wings and they left him alone. Another time, one flew back to the ledge with a tree*hopper or psil*lid attached to his leg. The others clawed at it until it finally let go. Very social behavior.