Thursday, December 20, 2012

Returning to the small streams in Sugar Hollow

It was sunny when I headed to Sugar Hollow this morning, but the clouds moved in in a hurry.  So, I can't say much about the quality of the photos you'll find in this entry.  Sun is a must for this kind of photography.  I also knew that the water was sure to be low.  It was, but I still saw a lot of insects: they were mostly in the leaf packs, but I saw a fair number of flatheaded mayflies on the bottoms of rocks.

In the photo above, the flatheaded mayfly, Maccaffertium merririvulanum.  I have still not seen this in any stream save for the small mountain streams that empty into the Moormans.  But these are the streams where ought to find them.  With a tolerance value of 0.5, this is the least tolerant flathead we find in our part of the country.

I've already gone into detail on this species in an entry posted on 1/17/12: I hope you'll have another look at that posting.  This is a flatheaded species that was first identified in 1978 in an article authored by Frank Louis Carle and Philip A. Lewis.  They note the pattern that is visible on the abdominal terga -- the pale "V"'s on segments 7-9.  They also note that the cerci (tails) are exceptionally long.  That's pretty clear.

But what's important for us is that this is a species that is only found in very small, very clean, spring-fed streams.  They even note that "The species has been collected from small pristine streams in the Appalachian Mountains."  And that's where I was this morning.   And as I noted on 1/17/12, M. merririvulanum is often found along with M. pudicum flatheads -- I also saw several of those nymphs  this morning.

The insect of the day?  The Giant stonefly, Pteronarcys proteus.  I didn't take any photos since I've posted so many photos of this one before.   I see more Giant stoneflies in the stream that I went to today than any other stream that I visit.  Some, at this time of year, are very big, but there are a lot of small ones as well.  P. proteus is an unusual Giant, having a growth period of 3-4 years (it's merovoltine).  (See Steven Beaty, "The Plecoptera of North Carolina," p. 28.)  So, it should not surprise us to see so many different sized nymphs throughout the year.

Other photos today:

1. A fair sized Perlodid stonefly, Malirekus hastatus.  This is a species that needs to grow into its head -- so to speak!  The head seems quite large in proportion to the rest of the body, but that changes when the nymphs are mature.  Note that the posterior edges of the wing pads have just started to curl.

2. A small Perlodid stonefly, Diploperla duplicata.  Here too, not much sign of a change in the wing pads.

But this is what those wing pads eventually look like.

3. Large winter stoneflies, Taenionema atlanticum, also a taxon we find only in this kind of stream.  They're growing, and they're plentiful.

4. A small winter stonefly, genus Allocapnia, possibly Allocapnia mystica.  It's a male: note the long "supra-anal lobe."

5. A Roach-like stonefly, genus Tallaperla.  These too are starting to grow and mature.  This one measured close to 10 mm.

6. And a Uenoid caddisfly larva, genus Neophylax.  I only saw two or three Uenoid cases this morning -- but that will change as the winter goes on.  I'm still hesitant to make a call on the species.  But, I have found a book that should help with this project: R.N. Vineyard, ed., The Caddisfly Genus Neophylax (Trichoptera: Uenoidae) (Toronto: Royal Ontario Museum, 2005).  A beautiful case.

I was surprised not to see any Chloroperlids (Green stoneflies), and I'm still not seeing the small minnow mayfly, Baetis tricaudatus.  Soon, I hope.

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