I promise I will frass this horrendous image as soon as I get an answer... These nymphs (attended by ants) were inside a blackberry leaf that was distorted by their feeding. At the time I assumed they were aphids, but just now in trying to determine what sort of aphid(s) do this to blackberry leaves, I came across a reference to a psyllid (Trioza tripunctata) that does this (and no clear references to aphids doing the same). Could these be psyllids? Some of them appear to have cornicles; does that rule out psyllids? I also don't see any images of psyllids with antennae that point backwards like this...