Saturday, April 18, 2015

You have to dig in the substrate: the "common burrower" (Ephemeridae), Ephemera guttulata

It seems that we find at least one every spring: the common burrower, Ephemera guttulata, the "Eastern Green Drake" to fly fishermen.   Unfortunately -- for the fly fishermen who live around here -- the tiny streams where I find them are lacking in trout.

To repeat what we use for species ID:  "Genus Diagnosis: Mandibular tusks divergent apically and curved upward in lateral view; frontal process of head distinctly bifurcate; small gills on abdominal segment 1 forked; abdominal gills held dorsally; ventral apex of hind tibia produced into an acute point."  (Beaty, "The Ephemeroptera of North Carolina," p. 44)  And on the species ID: "nymphs up to 20 mm; abdomen generally lacking any color pattern.  Collected mostly during spring and summer.  Mountains only.  Uncommon.  Recorded from GSMNP."  In the photo below, we can see all of those features but the forked gills on segment 1.  This nymph was a young one: only 14 mm.

Love to find this one since it's so different from the other nymphs that we see.  But you only find them if you dig around in the sand and silt.

(For more on E. guttulata (hatch times, fly patterns to use), see Knopp and Cormier, Mayflies: An Angler's Study of Trout Water Ephemeroptera, pp. 105-109.)

I was in Sugar Hollow this morning, and I started out at a very small stream at relatively high elevation, the one that I went to on 1/2/15 where I found the rare case-maker, Adricrophleps hitchcocki.  Today I didn't stay very long.  I was making my way upstream, the water clear and cold, when all of a sudden the water coming down from above turned muddy.  This is a steep incline and no one lives on the top of this mountain.  But something above me was walking around in that stream.  I was out of there!  This is bear country, and this is bear season.  And it's something I worry about when I'm up in the mountains at this time of year.

So it was in another stream further downhill that I found our E. guttulata -- actually, right in this pool.

Lots of spiny crawlers (E. dorothea) now showing up in the leaf packs, but my focus was elsewhere.

1. The Perlodid stoneflies, Isoperla similis, were a dime a dozen.

2. So too were the northern case-makers, Pycnopsyche gentilis, having here abandoned their three-sided case of leaves.

3. And on the bottoms of rocks, lots and lots of flatheaded mayflies, Epeorus pleuralis, many of them now sporting black wing pads (i.e. they're ready to hatch).


A good day -- just a great time of year to be out in the country in the state of Virginia.  (Below: entering Sugar Hollow.)


UPDATE:  There is a more detailed description of E. guttulata in the latest version of "The Ephemeroptera of North Carolina" (Version 4.0, July 9, 2013).

guttulata -- nymphs up to 20 mm; frontal process long, notch deep, approximately half the length of the entire process; body brownish overall; both fore- and hind wing pads heavily blotched with irregular dark spots; abdomen broad, generally lacking any distinct color pattern, both dorsally and ventrally." (p. 84)

Remember that Beaty's keys/descriptions/documents are available online at:

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