Small Streams -- Special Insects: A Report on Sugar Hollow

I'm keeping track of the insects I only find in the small mountain streams in Sugar Hollow.   Here are photos of the taxa I've noted so far.  (The stonefly nymph in the photo above is one that I have found in the Rapidan River as well: this is the Perlodid stonefly, Malirekus hastatus.  Still, it's a rather spectacular picture.)
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1. The flatheaded mayfly, Maccaffertium meririvulanum.

2. The freeliving caddisfly, Rhyacophila nigrita -- in cream/gray and aquamarine.

3. The freeliving caddisfly Rhyacophila glaberrima (species ID is tentative).

4. The common netspinner larva, Diplectrona modesta.

5. The fingernet caddisfly larva, genus Wormaldia.

6. The small winter stonefly, Paracapnia angulata.

7. The Perlodid stonefly Isoperla similis.

8. A Perlodid stonefly, genus Isoperla, species not yet identified by the professionals.

9. Another Perlodid stonefly, genus Isoperla, species not yet ID'd by the professionals.

10. And the giant stonefly, Pteronarcys scotti (species ID is tentative).

In addition to the Malirekus hastatus at the top of the page, there are three other taxa that I've only found in the small streams in Sugar Hollow and in the Rapidan River: the crane fly larva, genus Hexatoma, the northern case-maker caddisfly, genus Pycnopsyche, and the large winter stonefly, Taenionema atlanticum.  These.

Oh.  And I've seen Lepidostomatids in the Rapidan -- and elsewhere -- but Sugar Hollow's the place to go for beautiful "mixed media" (sand grains and leaves) cases.

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I'll be in Florida -- golf and fishing -- through next Tuesday, March 27.  I hope to post a new entry on Thursday, March 29.

The Common Netspinner "Diplectrona modesta" -- and Other Treasures from Sugar Hollow

I found a lot of nice insects today in the small stream I explore on the south side of the Moormans.  But it's the insect in the photo above that I was after.  The common netspinner (family: Hydropsychidae), Diplectrona modesta.  While stream monitors regard the common netspinner as a fairly tolerant insect, this genus and species is an exception: tolerance value, "2.3".  (At the moment, VA DEQ uses a TV of "6.0" for all common netspinners.)  But this is a species that most monitors never see, since we only find it in streams like the one that I went to today: a small, very clean stream in the mountains.

On Diplectrona common netspinners, the "meso- and meta-notum [are] divided by transverse fracture lines in [the] posterior third," and the "fore trochantin [is] simple" (i.e. not "forked" like those on Hydropsyche and Cheumatopsyche larvae).  (Text is cited from Barbara Peckarsky, et.al., Freshwater Macroinvertebrates, p. 101).    I have posted photos of these features in the entry for 3/4/11 -- please go to that entry to see the detail.  Other features noted in Peckarsky -- "Pronotum lacking transverse groove...constricted only slightly at posterior border; anterior margin of frontoclypeal apotome symmetrical and entire." (pp. 101-102)  These features are actually visible on the larva in the photo at the top of the page.  I've pointed them out in the photo below.

Also note in this photo that the anterior margin of the head is entire, lacking a notch, since that is one of the things that makes this larva Diplectrona modesta.  (On this point, see Steven Beaty's "The Trichoptera of North Carolina.")   The other Diplectrona species found in this part of the country -- Diplectrona metaqui -- is extremely rare.

Two more photos.  In the first, the netspinner has climbed up on the case of a Uenoid caddis; in the second, the larva has turned on its back, showing us the "common netspinner" gills.

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A few other treasures from my outing today.

1. A Perlodid stonefly, Malirekus hastatus.  I saw a lot of them -- all of them getting mature.

(Same insect; different lighting conditions.)

2. Two of the many Epeorus pleuralis flatheaded mayflies I saw.  The first has just recently molted and is almost transparent; the second is one that is fully mature (note the black wing pads.)

3. Flatheaded mayfly, Maccaffertium meririvulanum.  They're growing; note the long wing pads.  This was a big nymph: I'd say the body was about an inch long.

4.  Probably the largest spiny crawler (E. dorothea) that I saw today.  Pretty colors and patterns.

5. And a northern case-maker caddisfly larva -- genus Pycnopsyche -- in its 3-sided case made out of sections of leaves.  (Nicely layered -- I might add.)

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(Below: the wildflowers are blooming and the buds on the trees are opening up.  A nice time of year to go to the woods.)

The Small Minnow Mayflies Take the Day at Buck Mt. Creek

They're the only small minnow mayflies I see in Buck Mt. Creek in the winter and early spring -- Heterocloeon amplum, and they turned out in large numbers today.  This one is almost ready to hatch -- black wing pads.  But I found them in a variety of sizes and shadings, making the point very well that "hatches" don't occur all at once: H. amplums probably mature and hatch in Buck Mt. Creek from the beginning of March, through April, and possibly into May.

Let's look at the range of development that I saw today, working backwards from the mature nymph in the photo above.

1. A male  -- note the large, red eyes -- that is fully colored, still the wing pads have not started to darken.

2. Holding on to the back of the mature nymph in the photo at the top of the page, another male.  But note the light coloration, and, note how the eyes seem to be part red and part black (!)  I've seen this before in "teen" males, so I guess their eyes change as they mature.

3. Finally, an immature nymph that is still very light in color.  For a moment, I thought this might be an early sighting of the small minnow species Baetis intercalaris -- which I expect to see soon in this stream -- but, only two tails on this one, and the faint tracheation in the gills confirms that it too is H. amplum.

Too bad there are no trout in this stream.  If there were, fishermen could look forward to two months of "Blue-winged Olive" fishing.
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As for the rest of my findings today --

1. A real surprise -- a small winter stonefly!  This blew me away.  I was sure they were, by now, completely gone from our streams.  But, still a few late bloomers hanging around.

2. A spring insect that we find in this stream -- the "Net-winged midge," Blephariceridae, genus Blepharicera.  This is a very intolerant insect with a TV or 0.0.  Still, I normally find them -- as I did this morning -- crawling on rocks on which there are large clumps of black fly larvae.  Go figure.  Below, dorsal and ventral views.  Note the "suckers" on the ventral side which they use to cling to the rocks.

3. One of many Perlodid stoneflies, Isoperla namata.  (Two sources confirm the existence of I. namata in Virginia, so I'm dispensing with the tentative Isoperla nr. namata.)  They're showing up in large numbers in this stream as well.

4. And finally, the Perlodid stonefly that I see in this stream in a regular way throughout the winter -- Helopicus subvarians.

At the Moment, Not Much Diversity at the Rapidan River

Oh, there were a lot of insects today at the Rapidan River, but there was very little see but Isoperla nr. namatas (Perlodid stoneflies, as in the photo above) and Spiny Crawler mayflies, genus Ephemerella (E. subvaria, E. invaria, and E. dorothea, all three).  If you're getting ready to go out and monitor streams -- the spring sampling season is now underway -- then get ready to have samples that are dominated by these two taxa.

I did find other things.  I saw quite a few pronggilled mayflies, including one that was already mature; a couple of Giant stoneflies (P. biloba); a couple of Common stoneflies (Acroneuria abnormis); and a few Baetis tricaudatus small minnow mayflies.  I also saw Epeorus pleuralis flatheaded mayflies on the bottoms of rocks, common netspinners were under there too.  But the number of I. nr. namatas and the various Spiny Crawlers was simply staggering.  Look for big hatches soon of "Yellow Sallies," "Hendricksons," and "Pale Evening Duns"!

Nothing but photos today.

1. The Isoperla nr. namatas, the most common Perlodid stonefly we find in our streams, are rapidly maturing.  So they are very colorful and richly patterned.

2. A mature pronggilled mayfly (genus Paraleptophlebia) -- with a few gills missing, I'm sorry to say.

3. Baetis tricaudatus, the small minnow mayfly we find in the mountains.

4.  One of two Ephemerella subvarias (Spiny Crawlers) that I located today.  These, too, are rapidly getting mature.

5. Ephemerella invaria.

6. And two more Spiny Crawlers, in a photo that sort of sums up what I saw today in my tray.

Heterocloeon amplum: Our Small Minnow Mayflies Mature

I haven't done much serious fishing since I moved to Virginia (2003), but were I to head to a stream in March and April, I'd be sure that my "Blue-winged Olive" patterns were easy to find in my vest.  Baetis tricaudatus (see the entry posted on 2/23) and Heterocloeon amplum -- the small minnow in the photo above -- are both ready to hatch.  The long, black wing pads are a sure sign of that.  (Cloudy days with sprinkles, probably mid-afternoon, and I'd use a size 14 hook: these are pretty big bugs, and they usually come off in large numbers.)

I finally got back to Buck Mt. Creek.  Rain followed by snow have kept our streams running high and off-color.  The water was still high today -- but clear.  I was hoping -- and expecting -- to find two insects: maturing H. amplum small minnow mayflies -- success; and maturing Nemourid stoneflies -- there I struck out.  I'll be heading up to the Rapidan River this weekend, where I'll be seeing Nemourids for sure.

Actually, I think I found more H. amplum nymphs today than anything else.  Still the collection included 3-4 stunning Clioperla clios (a Perlodid stonefly); some large winter stoneflies -- Strophopteryx fasciata (I was beginning to think they had all hatched); one large Spiny Crawler, a "twin" to the one I found yesterday; a few Diploperla Perlodid stoneflies; and I did find a good Hydropsyche common netspinner larva -- so far, the ID eludes me.
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1. A few more pictures of the H. amplum nymphs.  I found both females (above) and males (the one below with the big eyes).

2. Common netspinner larva, genus Hydropsyche: dorsal and ventral views: size about 14mm.

I was hoping that the orange abdominal terminus would help with species ID, but apparently not (using Steven Beaty's "The Trichoptera of North Carolina").  I'll continue to work on this larva and get back to you if I can ID it.

3. A nicely maturing Diploperla duplicata that chose to float on top of the water.

4. And finally two of the Clioperla clios) that I found.  The colors were simply stunning.  The light tipped wing pads on the second nymph is something I've not seen before.