Saturday, May 19, 2012

Nothing New at South River -- But Quite an Assortment of Insects

I found nothing new at South River this morning, but I did see a whole lot of insects, most with pretty long wing pads -- i.e. getting ready to hatch.

Mayflies: There were still quite a few spiny crawlers around - E. dorothea -- though nothing like the numbers I saw the last time I was here.  The one that caught my eye was this lovely genus Eurylophella, probably Eurylophella verisimilis.  I'm still fascinated by those large, operculate gills on tergite 4 -- sticking out to the sides on this male -- that cover, and protect, the gills on tergites 5-7. They're somewhat tolerant, obviously because they're not bothered by crawling in silt!  (I only rarely see a clean one.)

2. I also saw a fair number of brushlegged mayflies (Isonychia bicolor).  They were big -- but the wing pads were quite a bit shorter than those on the nymphs I saw at the Rapidan River.

3. Pronggilled mayflies (genus Paraleptophlebia):  Actually, I only found one.  I wasn't surprised to that they're in here, this is the habitat that they prefer (clean, cold, mountain stream).   But this is the first one I've seen in this river.

4. Epeorus pleuralis flatheaded mayflies.  The bottoms of rocks were still covered with these nymphs up here.  I'm surprised to see them around this late in the spring, but, the wing pads show that they'll be taking off -- literally! -- very soon now.

Stoneflies:  I saw two common stoneflies (Perlids) -- a large one that will be hatching soon and a small one that will be hatching next year.  But I saw large numbers of two different species: Isoperla holochlora and Remenus bilobatus.

I. holochlora -- normal color:

I. holochlora -- one that's unusually yellow:

Remenus bilobatus: I photographed two of the many I saw -- both were fairly mature, and the one had dark markings showing up on the wing pads.

Caddisflies: Saw a few fingernet larvae, genus Dolophilodes, and a couple of freeliving caddisfly larvae, both R. fuscula.  But what did I see in large numbers?  Glossossomatids (Saddle-case makers)!

Time for me to read up on this caddisfly family.  I always see them in the winter, but here they are once again in late spring.  In the photo above, you can see the larva's front legs sticking out of the case.  But I got some good photos of the larva moving to get out of its case once its "dome" had flipped over.  (It never did leave its case, by the way, and it's now safely back in the river.)

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