Thursday, March 8, 2012

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.

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.

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