Eriosoma lanuginosum-Hemiptera-Sternorryncha-Aphididae-galla su foglia
Identified for me by John Ascher, BugGuide, Iowa State University.
Found under a rock. Maybe isopods or aphids? I have no clue. Size is tiny: about 1mm each.
A female Aphididae and maybe a male under her, followed by some ants... What is this behavior ?