Moving On

It's a beautiful photo -- and a sign of spring.  And I think for me too, it's time for a new beginning.

I've run out of things to say.  I've done about as much as I can do on family ID and genus ID, even species ID with some of the mayflies and stoneflies.   To keep on going, I'll simply be posting more photos -- and repeating things that I've said, in most cases more than one time.

So, I've been pleased with the response to this blog, and I hope that people have learned something about aquatic insect ID from the entries I've posted and have come to appreciate the beauty of these insects from the photos I've taken.

I will continue to post new photos at:
http://www.flickr.com/photos/aquaticinsects_of_central_virginia

Look in "live photos only."

Best wishes,

Bob Henricks

"Two" Large -- and Other Treats From South River

Yes, it's "two," not "too!"  I'm not sure how I managed to get them both into focus.  On the bottom, the large winter stonefly Taenionema atlanticum; at the top, the large winter stonefly, Taeniopteryx burksi.

I went to a new stream today, the South River, a small stream that flows out of the Blue Ridge and passes to the north of Stanardsville, VA.   I followed it up into the mountains, so it was not very big where I decided to stop and have a look at the insects.

Every rock I turned over was covered with flatheaded mayflies -- all Epeorus pleuralis -- and every leaf pack I looked at was crawling with large winter stoneflies, among other things.  Let's look at the show.

1. A Spiny Crawler mayfly -- Ephemerella dorothea.  I couldn't believe it!  I expect to see these in March -- our streams are loaded with them in March and April -- but January 5th?  You never know what you're going to see.

2. Another surprise -- another small minnow mayfly, but this one was Baetis pluto.  So, I've now seen this small minnow species in four different streams at four different times of the year -- in May, June, October, and January.  Note that the middle cercal segment (tail) is much shorter than those to the sides, and that tergum 5 is pale, while 6-8 are dark.

3. And another surprise -- a fully mature large winter stonefly, Taeniopteryx burksi.  Note the dark wing pads, which mean that this one is ready to break that skin open and fly.

Gorgeous!

4. And yet another surprise -- a green free living caddisfly larva, but it isn't Rhyacophila fuscula -- no dark, partial "H" on its head.   It's pretty wierd.  I've got to work on this one a bit, and if I figure it out, I'll let you know.  I took a quick look at Beaty ("The Trichoptera of North Carolina"), but I can find nothing described as having a head that's lime green.

_____________

The rest of my findings were things I'd expect to find in a quality, mountain, stream at this time of the year -- but things of beauty nonetheless.

1. The flatheaded mayfly -- Epeorus pleuralis.  This was probably the dominant taxon today: they were crawling all over the rocks.  They're easy to spot.  They do not move in a straight direction; they always angle off to the side, whether moving ahead or retreating.  And this is their season.  They will hatch in March and April as "Quill Gordons" (to fly fishermen).  Note the short wing pads -- and this is one of the larger nymphs that I saw.

2. Uenoid case-maker caddisflies.  I saw quite a few on the sides of the rocks, but just picked out this big one for taking a picture.  Pretty case.

3. Prong-gilled mayfly nymphs -- genus Paraleptophlebia.  There were a lot of them.

4. A Perlodid stonefly, genus Isoperla for sure, probably I. namata (but not a call I'm ready to make).

5. And, here are some more Taenionema atlanticum large winter stoneflies.  I did not see the large winter species Strophopteryx fasciata at all in this stream.

It was a long drive -- but well worth it.  I'll be heading back there next month.

Re-Cap, Fall, 2011: First Sightings of the Perlodids

Last fall, I found six Perlodid stonefly genera -- immature nymphs -- and three species of one particular  genus:  Isoperla.  The only Perlodid genus I have not yet discovered -- one that I did find last winter -- is the one pictured in the photo above, the genus Yugus.    I found this nymph in the Rapidan River on March 24th.  I hope to see it again -- but I don't think it's at all "common" in our streams.

Here is the sequence of discoveries I made in the fall (i.e. in this new season) along with photos of the immature nymphs.  Keep in mind that any species of aquatic insect will first appear at different times in different streams.  Things vary with location and water temperature, and I suppose the two things are related.

1. Isogenoides hansoni: 9/13, Rapidan River (the tolerance value remains undetermined)

This is a genus and species that I have only found in the Rapidan River.  I found a second, larger, one on 10/21.

2. Clioperla clio: 10/25, Doyles River (tolerance value is 5.2)

This species is fairly common and shows up in large numbers in the streams that it inhabits.
This season, I've found C. clio nymphs in the Doyles River, Buck Mt. Creek, and in some of the tributaries to the Moormans.  I know they are common in the Lynch River as well.

3. Helopicus subvarians: 11/3, Buck Mt. Creek (tolerance value is 1.2)

Again, not a Perlodid that I've seen in a lot of our streams.  This season I've seen them in Buck Mt. Creek and the Doyles River, the same streams in which I saw them last year.

4. Diploperla duplicata: 11/8, one of the tributaries to the Moormans (tolerance value is 2.8)

This is a species that is fairly common.  I found it last year in Powells Creek, Buck Mt. Creek, the Doyles River, and the Lynch River -- and probably other locations which I cannot at the moment recall!

5. Isoperla similis: 11/12, one of the tributaries to the Moormans (tolerance value 0.8)

I. similis nymphs are simply gorgeous, and I can't wait to see mature samples sometime in March.  I have found this species in three different tributaries to the Moormans -- all small, clean, cold water streams: I've not seen it anywhere else.

6. Isoperla namata: 11/19, Rapidan River (tolerance value is 2.5)

You may recall that I wasn't really sure which Perlodid this was on 11/19: I felt more confident with the nymph I found on 12/13.   This is the species I think of when I think of "Perlodid."  We see it in a lot of our streams and in very large numbers, mostly in March and April.

7. Isoperla holochlora: 12/26, tributary to the Moormans River (tolerance value is 0.7)

I'm not 100% on this call -- but I'm fairly confident.  We don't see this one a lot, and it seems to mature later than most other Perlodid species (May and June?).  I've seen them in the Moormans tributaries, the Rapidan River, in Powells Creek, and in Buck Mt. Creek.  Very pretty -- one of my favorites.

8. Remenus bilobatus: 12/30, Moormans River (tolerance value is 0.9)

_____________

This does not exhaust the list of Perlodids I'm hoping to find.  I have yet to see Isoperla nr. holochlora -- Isoperla near holochlora (tolerance value of 0.0).   Last year, I saw this only in the Rapidan River.  It is indeed "close to" I. holochlora in appearance, but the head pattern is not quite the same.

And you may recall that last year I found two Isoperlas in tributaries to the Moormans that remain unidentified by the experts in terms of the species.  These:

Oops! Make That Genus "Remenus"

I have to correct my mistakes when I find them.  This little Perlodid stonefly that I found in the Moormans on the 12/30/11 was not a Diploperla Perlodid -- as I so boldly proclaimed without doing any microscope study -- it was a Remenus Perlodid.  Another first for the season.

Remenus is a Perlodid genus that I found in only two places last year: first at Buck Mt. Creek on 5/31, and then the very next day, 6/1, in a tributary to the Moormans.  So, here's what they look like when they grow up.

5/31, Buck Mt. Creek:

6/1, tributary to the Moormans:

If you go back to the entry I posted on 5/31, you'll see that the key feature that distinguishes the genus Remenus from other Perlodid genera is the lacinia:  it has only one tooth -- no other spines or hairs.  And here's what I saw in microscope today when I took a close look at this nymph.

(I thought at first I had broken a second tooth off -- but no: the other lacinia was exactly the same.)
Perlodid stonefly, genus Remenus.  And, the only species that is known for sure in North Carolina is Remenus bilobatus, TV = 0.9 (NCDWQ).

Sloppy work on my part.  Sure looked like Diploperla, but clearly, we can't base ID on our "hunches".  That also means, that I do not know the genus of the other Perlodid I found -- the one that had just recently molted and was almost transparent.

Strophopteryx, Strophopteryx, Strophopteryx! Must be January at Buck Mt. Creek

The large winter stonefly, Strophopteryx fasciata -- as in the photo above -- will probably dominate my findings at Buck Mt. Creek for the next month to month and a half.  This morning they were all over the place, both on the bottoms of rocks and in the leaf packs.  Of the insects I collected to look at -- I found one Helopicus Perlodid stonefly, three or four Clioperla Perlodid stoneflies, two Uenoid case-making caddisflies, one small minnow mayfly (more about that in a moment) -- and twenty to thirty S. fasciata large winter stoneflies.  I didn't see a single Taeniopteryx large winter stonefly -- though I'm sure there are still some around.

And I found small nymphs, medium-sized nymphs, and some nymphs -- like the one in the photo above -- that are already pretty darn large.  E.g.

Small

Medium

Large (not the same nymph pictured in the photo above)

If you monitor streams and you see nymphs that look like this -- yellow and brown, or yellow and green, with "mottled" head, pronotum and wing pads, and clearly banded abdominal segments -- you've
found large winter stoneflies.  But, you want to be careful: keep a few for "certain ID" in your lab.  This is the large winter with the "triangular, ventroapical plate," and that's not necessarily something you'll see with your loupe.

And let me remind those who monitor streams that this is one place where Voshell's Guide to Common Freshwater Invertebrates can be misleading.  The large winter stonefly that he shows in his book on p. 134 (plate 47) is Taeniopteryx burksi (with coxal gills) -- this one --

 and this is not the most common large winter stonefly we find in a lot of our streams in this part of Virginia.  Come late December, in the streams that I look at, S. fasciata large winters will out-number T. burksi large winters ten to one (well, I haven't counted -- but you get my point).  Voshell's book is so important for those of us learning family ID of these insects that I wish he had said more about this.
_________

We move on...  My big surprise for the day was finding this little nymph.

Yes, indeed -- it's the first small minnow mayfly of the new year and new season.  It's great to see them return, and the numbers will increase in this stream and others (the Doyles, Powells Creek, the Lynch River) as we move from January to March.  I am quite sure that this is the same species that I saw in these streams in the winter last year, and I'm fairly sure it's Heterocloeon amplum.   Note that it has only two tails: that means that the genus is either Acentrella or Heterocloeon (all Baetis nymphs have three tails), and it sure isn't A. nadineae or A. turbida -- it's a Heterocloeon.   But let's look at the ID issue in greater detail when we have larger specimens that we can examine.  Still, you can probably note the resemblance to this H. amplum nymph that I found in Buck Mt. Creek in March of last year.

And to finish things off today, pix of two of the Perlodid stoneflies found today.

Clioperla clio

Helopicus subvarians

Oh, and we can't forget the Uenoid case-maker caddis.

_________

Below -- my favorite sight as I drive out to Buck Mt. Creek.