Steven Beaty kindly replied to my question about the distinctive head pattern on two of the Clioperla clios that I found yesterday. He agrees that it's odd and finds it of interest. He suggested -- one of my thoughts on this yesterday -- that this might be because it's very mature, close to hatching, and the adult head pattern might be showing through the integument. (For a picture of an adult C. clio, go to http://bugguide.net/node/view/403320/bgimage.)
What is odd, remember, is the intrustion of black -- from bottom and top -- into the large yellow/orange space in the center of the head. This is what we normally see:
(But note that even on this nymph, the dark pigment between the rear ocelli seems to be moving towards the anterior ocellus.) So, an interesting find, about which we may hear more later on.
On another matter, the Spiny Crawler in the photo I posted yesterday (on the left side below), turned out to be Ephemerella dorothea, not Ephemerella invaria: absolutely no tubercles on the back edges of the abdominal tergites.