This specimen appears to be of the same species as this one collected in the same spot two months earlier. The identification of both is tentative. This one suffered some physical damage before being photographed, too, so the colors aren't totally natural. I was mostly photographing it to test out some new camera setting idea, which worked really well for a couple of closeups.
Martinlf on Dec 23, 2006December 23rd, 2006, 12:21 pm EST
That sounds like some southern jive tune, doesn't it?
I seem to recall that we had a discussion about mayfly shucks a while back, in which we discussed the more opaque and dark coloration of invaria or rotunda shucks. These acerpenna shucks look much lighter, and greyish in color. Am I right? Are they also more translucent? What color are the nymphs, and what color Z=lon would you use to imitate a shuck on an emerger for this bug? Would this hold true for most baetids? This might explain the excellent luck I've had with the Little Lehigh olive emerger, (basically an RS2 design--see the Litle Lehigh Fly Shop website) which has a shuck of natural CDC that is fairly greyish in color.
Also, the first picture shows a clear difference in the color of the top and bottom of the abdomen, another good cue for dubbing color. Jason, these photos are amazing! I hope you have some luck with photos of emergers in the spring.
"He spread them a yard and a half. 'And every one that got away is this big.'"
GONZO on Dec 26, 2006December 26th, 2006, 12:28 pm EST
The greyish shuck in the photos is the shed pellicle of the dun as the adult transforms into a spinner. The grey (dun) color reflects the duller coloration of the subimago and should not be taken as indicative of the nymphal shuck. I believe that most Acerpenna nymphs are brown to brownish-olive. Most mayfly shucks are more substantial and retain more color than caddisfly shucks. I assume this is because the exoskeleton has more of a protective/camouflage function for final stage mayfly nymphs than for caddisfly pupae (which transform into the pharate adult stage within a shelter). Of course, paler mayfly nymphs (like some burrowing nymphs) will have more translucent shucks (less pigment).