Friday, February 24, 2017

Mayflies, Stoneflies, Caddisflies: A real mix today at Buck Mt. Creek

It was the kind of morning I really enjoy:  sunny, warm (74º!), and the insects were plentiful, varied, and easy to find.  Let's look at some photos.

1. Large winter stonefly, Strophopteryx fasciata, pictures above and below.

There were a lot of them in the leaf packs, and some, as you can see, were fully mature.  In fact, I saw some adults flying around, and I think they were S. fasciata.  The one below landed on a rock where I was working.

I can't ID winter stonefly adults, and I found some small winter stoneflies that were also mature,

but my photo seems a good match for the S. fasciata picture that Donald Chandler has posted (

2. Small minnow mayfly, Heterocloen amplum.

This is the only one that I saw which surprised me: they ought to be out in good numbers at this time of year.  But I see them right into April, and in April they hatch.

3. Another stonefly -- a Perlodid stonefly -- Helopicus subvarians.

It's a beauty, and it's fairly common in Buck Mt. Creek.

4.  Giant stonefly, Pteronarcys dorsata.

With a tolerance value of 2.4, it's the most tolerant of Giant stones.   I've seen it before in Buck Mt. Creek, and it's the species I also encounter at the Rivanna.  A good distinguishing feature for P. dorsata is the sharply produced corners on the pronotum.

5. Common netspinner, genus Cheumatopsyche.

Actually there were two in the same bunch of leaves.


6.  But there was one thing I was really hoping to find and I did, and again I found two.  Nemouridae -- "Spring Stoneflies" or "Forestflies".

To ID these to genus and species, I need to do some microscope work.   Previous work on these nymphs has led me to two different ID's: Prostoia completa and Ostrocerca truncata.   Let me see what I arrive at this time, and I'll post my results in a separate entry tomorrow.

Great to see such variety, but it's what we get in the spring!

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