Tuesday, May 24, 2016

Some awesome photos today: back to Sugar Hollow


Tough to know where to begin today: we found some beautiful insects.

Above, our as yet unidentified species of Isoperla ("stripetail") .  Consequently,  Beaty et.al. have it labelled Isoperla sp. VA.  As I noted last time, we're on the lookout for some nymphs that are fully mature, nymphs we can rear to point that they hatch.  This one's not quite there, but the "tan" wingpads are one instar before they turn black.  So I kept him just in case I get lucky.



The stream that we went to today -- the little gem where my friend lives -- was loaded with them.  I took two nets and had 10-12 in my tray.  Have to look next week for some that are fully mature.
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And then we have the Leucrocutas.  What a gorgeous insect.  Pretty sure this is L. juno, but as you'll remember, entomologists want to hold off on species ID until more work has been done.  In any event, they too were abundant today.  I took photos of this mature nymph and one that's still sort of young.




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Finally, a young Stenacron nymph.  You might recall that the distinguishing feature of Stenacron nymphs is the shape of the gills: they come to a point.


Beaty: "Abdominal gills 1-6 with apex pointed, seventh gill filamentous; three caudal filaments." ("The Ephemeroptera of North Carolina," p. 22)

This nymph is Stenacron carolina, and the key thing to examine is the pale spot on the head.  "S. carolina -- nymphs 10-13 mm; length of pale triangular spot anterior to median ocellus approximately 2X it's basal width (provisional) ...dorsum of abdomen grey-brown without conspicuous markings; caudal filaments all light grey brown with no banding.  Usually in small mountain streams.  Collected spring to summer.  Uncommon." (p. 22)

You can see that "pale triangular spot" very well on almost all of my photos.




And here's a microscope view.

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So satisfying to find some good insects and get decent photos.  Up to the Rapidan River tomorrow.
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Oh, by the way.  Steve Beaty joined us at this stream last month.  That's him on the right.


Friday, May 20, 2016

It's the annual "spiny crawler" invasion: Ephemerella dorothea


Actually, they're kind of a nuisance at this time of year.  For the last 3-4 weeks, when I sort through my tray to see what I've collected, it's hard to get past these spiny crawlers.  It has to be one of the biggest hatches all year, and they come out as -- in fly fishing terms -- PED's, Pale Evening Duns.  Early on in the year we tend to see Ephemerella invaria, but Ephemerella dorothea dominates the invasion each spring.  The main clue for the ID -- no turbercles on the posterior edges of the abdominal terga.


In a previous life when I monitored streams, I had the impression that when spiny crawlers dominated our net counts, we had hit upon a poor quality stream.  Just not true.  It's just what we run into at this time of year.  This morning I was at one of our headwater streams in Sugar Hollow.  My tray was loaded with them.  I normally ignore them when I'm taking photos, but I thought the colors on this one were nice.
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My search for Isoperlas continues, but I think I'm too late for anything but I. holochlora.  Still, I found this mature Isoperla sp. VA on May 18 in 2011, so there's hope.


I know Steve Beaty would LOVE me to rear one of these till it hatches.  We need an adult to detemine species ID, and, this could be a brand new species.
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Two nice pics from this morning.  The first, a flatheaded mayfly, Maccaffertium pudicum.


And the second, a pair of small Perlestas.  Guess they do inhabit these cold, mountain streams.


Monday, May 16, 2016

Just back from Entry Run: no surprises but some good photos


So disappointed.  I was up pretty high on Entry Run -- 1600 ft. -- but nothing different than the insects I find down lower.  Only Isoperla I found: Isoperla holochlora.  Need to get up even higher.
But, at least the sun is back out!


Baetis tricaudatus, the small minnow mayfly we find in these high quality, small mountain streams.  As you can see, this one was ready to hatch.  Put it back in the water.

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And the common netspinner we find in these streams: Diplectrona modesta.  This one's much more intolerant (TV 2.3) than the Hydropsychids we find in larger streams.  I keep thinking I'll run into Diplectrona metaqui, though it is listed as "rare".  (Beaty, "The Trichoptera of North Carolina," p. 74)
D. metaqui has an asymmetrical notch on the anterior margin of the head: on D. modesta, the margin is "entire" (= straight across).  Like this.

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Found two Haploperla nymphs.  One was quite immature.


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And there were a lot of Acroneuria abnormis common stones.  This was the biggest.




But it sure was a beautiful stream.  Boulder-strewn.


Sunday, May 15, 2016

Perlesta stoneflies -- still have to leave them at the level of genus


A little surprised by this one this morning -- not that we shouldn't be finding Perlestas (common stonefly, Perlidae) at this time of year -- this is when we normally see them (May, June, July), but I was in a small mountain stream.  Don't see many Perlids in this type of stream other than Eccoptura xanthenses.  That means that there are Perlestas in most (all?) of the streams that I visit, from these small, first order streams, to medium streams like the Doyles and Buck Mt. Creek, to our large river, the Rivanna.

While most Perlids are multivoltine (life cycle of 2-3 years), Perlesta is not.  It matures, hatches, and mates within the space of a year (univoltine).  And, unfortunately, we're still in the dark on the question of species ID.  As I've mentioned before, Steve Beaty published online a revised version (4.1) of "The Plecoptera of North Carolina" just last year in December.  But his advise on Perlesta remains the same: "LEAVE AT GENUS".  (p.48)  He lists the names of 13 different species but notes that "most of [these] are currently undescribed in the immature stage." (p. 49)  So we wait.  I have no doubt that the species that I found today is not the same as those that I find in the Rivanna.

I had high hopes of finding some new Isoperlas today, but all that I saw was I. holochlora.  Maybe tomorrow at Entry Run up in Greene County.

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Just two other pics from today.  A fairly mature Ameletid: Ameletus cryptostimulus.  (There were a lot of them.)


And a small Leucrocuta flatheaded mayfly, the one that I think is Leucrocuta juno (see the entry of 5/27/15).   Regret that the tails aren't fully intact.




This too, is a species I only see in first order streams.

Thursday, May 12, 2016

Tough conditions -- but an important discovery


Horrible weather!  Rain, clouds, fog, day after day.  But I had to get out of the house.  So, I ventured out to the Upper Doyles River to see what I could find.  Finding insects wasn't a problem but taking photos was a different matter completely.  I took 59 photos today -- I kept 3 to edit.  I sure hope they're right about the sunshine this weekend.

Above, one of the photos I kept and cleaned up a bit.  The "brushlegged" mayfly, Isonychia.  Beaty says we should leave this at the level of genus.  ("The Ephemeroptera of North Carolina," p. 15)  I had 3-4 of these in my net, all of them like this one, very dark = very mature.  These nymphs tend to hatch in June and July in our parts.  Early on, they look more like this.

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Another one of my photos, the Perlodid stonefly Remenus.


I believe I've noted before that this is the last Perlodid I see at the end of each season.  We start to see them, end of April/early May, and they hang around until June/July.  Hate to say it, but it's a thoroughly boring Perlodid -- not much to look at in color or pattern.  Alas.  Remenus is the Perlodid with the lacinia that's "unidentate" -- one tooth.

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This is the third photo I kept.


It's a terrible photo, but I wanted it for documentation.   Isoperla orata, and this is the first time I've seen it outside of the Rapidan River.  Note the distinctive abdominal pattern: the pale areas on the abdominal segments are completed surrounded by a dark border.


This species was first described by Frison in his work, "Studies of North American Plecoptera," Natural History Survey Division: Bulletin, 22:2, September, 1942, pp. 323-325.  On the abdominal pattern he said, "Longitudinal dark stripes on abdominal tergites tend to be connected on hind margin of segments by narrow transverse line which gives tergites somewhat the appearance of having cell-like light spots each side of median, longitudinal stripe."  Bingo.  Here's one that I found in late May at the Rapidan River: they'll be maturing real soon.


Until today, I had only found the variant form of this species at the Upper Doyles River, the one on which 1) the median line on the tergites is much more pronounced and 2) the pale spots do not look like cells.  This one.



So at the Doyles River, as at the Rapidan River, the two forms co-occur.
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Praying for sun!
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Oops!  I totally forgot.  A few weeks ago, I was going back through my files and found this.


It's also Isoperla orata, and this one was in one of our small headwater streams in Sugar Hollow!  May 2, 2012.  Guess it's in more of our streams than I thought.

Wednesday, May 4, 2016

The "tiny" Green stonefly (Chloroperlidae), Haploperla brevis


The rain doesn't want to let up.  We've had over 3 inches in the last few days with more on the way.  So, we're very restricted at the moment in terms of the streams that we can explore.  It's a bummer, since this is THE time of year to find so many good insects.  Moreover, the cloudy, drizzly weather makes photography very difficult.  The photos today are not very good: I cranked the ISO up to 400 and used the flash, but that sacrifices detail.  We take what we can get.

I decided to look at the Whippoorwill Branch of the Mechums.  It's very small and tends to stay clear even in rainy weather.  And I was very pleased to find this little stonefly: this is only the third one that I've seen.  It's the Green stonefly, Haploperla brevis.  (I've found it in this stream before.)

Beaty notes the "key" features as follows: "Genus Diagnosis: Nymphs - 7 mm...pronotum with sparse setae, longest and most numerous at anterior corners; long pronotal fringe hairs are at least 0.3-0.4 times the pronotal width; inner margin of hind wing pads subparallel to body axis; pronotum and tergites lightly setose...body light brown, nearly concolorous." "H. brevis -- fits genus description." ("The Plecoptera of North Carolina," p. 9)  He adds, "Primarily found in gravel and riffle ares of small to medium streams."  That's where I was looking.  Tolerance value for this one is 1.4.

The nymph that I found this morning was very small, only 6 mm, but it's easy to see that, yes, the color is light brown, the entire nymph being much the same color.  For more detail on diagnosis, we need microscope photos.

As you can see, the hind wingpads are subparallel, and in this shot you can see at least 1 seta on the pronotum with many more at the posterior corners.


For the long setae at the corners of the pronotum, we have two photos.  You can judge for yourselves on the length of the longest of setae.  I have no problem calling them 0.3 - 0.4 times the width of the pronotum.




I've wondered this morning about the species ID.  Beaty describes another species -- fleeki -- that is tempting as well.  "pronotum with antero- and posterolateral margins dark, contrasting with light brown almost diamond shaped interior; abdominal tergites with transverse banding along posterior margins slightly widening laterally."  With our nymph, the prontoum has a dark margin, but it's around the entire pronotum save for medial interruptions on the front and back edges.


Moreover, there does not appear to be banding on the terga.   One other thing, apparently H. fleeki has only been found in the "Sand Hills" of North Carolina: brevis is collected "from [the] Mountains and Piedmont.  Think we've got H. brevis.
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I saw a variety of insects today -- spiny crawlers, some rolled winged stoneflies, and lots of fingernet caddisfly larvae.  And there were quite a few small minnow mayflies, which turned out to be Baetis pluto.


There are two features that give this one away.  1) On B. pluto nymphs, there is a pale area/line parallel to the eye, and 2) "tergum 5 [is] relatively pale, [while] segments 6 and 7 [are] almost completely dark."  (Beaty, "The Ephemeroptera of North Carolina," p. 6)

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May the sun come out soon and the streams drop and clear.

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Note:  According to Nature Serve Explorer, H. fleeki has only been found in North Carolina.