Friday, November 7, 2014
The Perlodid stonefly Helopicus subvarians appears at the Doyles
First of the season: Perlodid stonefly, Helopicus subvarians. It's one of the few stonefly nymphs that we see that's colorful from the very beginning. It's also one of the biggest -- longest -- Perlodid stoneflies we see -- 17-20 mm when it's mature. And they're quite striking when they're mature.
2/27/14 -- not yet mature.
3/14/12 -- fairly mature
2/6/12 -- very mature.
According to Stewart and Stark (p. 400), subvarians is the only Helopicus species we find in VA, and the distinguishing feature of this particular species is the fairly straight anterior edge of the dark transverse band on the head (Beaty, "The Plecoptera of North Carolina," p. 21). While that straight edge is very clear in the 2/6 photo above, that is not the case with the immature nymphs from this morning.
With a tolerance value of 1.2, it's a species we find in fairly clean streams. I always see lots of them in the Doyles and at Buck Mt. Creek.
Another day when taking photos was tricking: breezy with fast moving clouds. Still, awfully nice out there at the moment.