Sunday, August 9, 2015

Montana, 2015: some old some new

Another wonderful trip to Montana.  We fish out of Missoula, floating -- this year -- the Blackfoot River, the Upper and Lower Clark River,  and Georgetown Lake, one of my favorite places.  We also waded Rock Creek.  In the insect department I found a number of new things, but I also found a number of Tricos (Leptohyphidae, genus Tricorythodes).  They were hatching on all of the rivers.

The long middle tail is one of the keys to identification.  So too are the triangular, operculate gills.   (For the nymphs and larvae I find in the Northwest, I use the keys provided by Flyfishing Entomology.  For the descriptions of mayflies, go to

We found prolific hatches of Tricos, especially on the lower Clark Fork.  My friends took some really nice fish (19", 20"), using dry fly imitations.  While we have Tricos in our Virginia rivers as well, it's unlikely that we have the same species.  These apparently are Tricorythodes minutus.

But I was delighted to find something new.  Number one -- the flatheaded mayfly, Heptagenia solitaria (Gray Fox, Ginger Quill Spinner).

For the description, see the Flyfishing entomology website at the same site noted above.  Quoting that source: "Heptagenia -- Similar size and shaped gills on all segments; additionally, fibrilliform gills on segment 7 as well as on other;  tarsal claws with single basal tooth, no denticles.  3 tails.  solitaria -- Paired white spots on tergites; tufts on 7th gill."   My photos of the tarsal claws just didn't turn out.  But the other features are clear in the photos above.  For a closer look at the fibrilliform on segment 7 and the paired light spots on the terga, here's a microscope photo to use.


Number two was a new common stonefly (Perlidae), Hesperoperla pacifica.   Found this one at Rock Creek on a rainy, dark, cloudy day.  For photos this is the best I could do.

As you can tell from the short wingpads, this was a young one.  It will probably hatch sometime next summer (Golden Stone).  For the genus and species descriptions we turn to the following page:  "Hesperoperla --Paraprocts are small and triangular and 9th seg bears a large quadrangular hammer, females have moderately produced subgential plate.  pacifica -- Nymphs w/wide longitudinal (hourglass-shaped) yellow band extending from middle ocellus to labrum; fluffy white gills between its tails.  Habitat preference: fast rocky runs & riffles."   Rock Creek is a "fast rocky run."

Not sure of the gender ID, but to me this looks like a male.

For other features --

I found two other things at Rock Creek that I need to ID -- a mayfly nymph and a cased caddis.   I'll post photos of those when I know what they are.   But, my live photos were too dark and too blurred (even at ISO 400 and using the flash!), so microscope photos will just have to do.  More to come.

And this is the kind of Trout we find up at Georgetown.

Georgetown Lake

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