Thursday, October 6, 2011

Stream Report: The Rapidan in Autumn

I got some wonderful photos today -- perfect weather conditions.  So, for the most part, this will be a posting of pictures.  The report is that everything's growing: here as elsewhere, what I'm seeing are the young insects that will mature over the winter and hatch sometime next spring.  I found a lot -- and I mean "a lot" -- of tiny brushlegged mayflies.  I have some photos of one of the more colorful ones: most were still rather pale and lacking in color.  Lots of Perlids (common stoneflies), mostly genus Paragnetina, with the occasional Acroneuria thrown in for good measure:  Peltoperlids (Roach-like stoneflies), like the one in the photo above:  one medium-sized Giant stonefly: a few fingernet caddisflies, genus Dolophilodes: lots of tiny, most of them anyway, flatheaded mayflies (genus Maccaffertium: a couple of small free-living caddisfly larvae: and a few small minnow mayflies -- Baetis intercalaris -- that will still be hatching sometime this autumn.


1. Another look at this small -- but no longer a "baby" -- Peltoperlid, a very unusual angle.

2. A couple of shots of one of the many Paragnetina common stoneflies that I saw.  Stunning colors and patterns!

3. The Dolophilodes fingernet caddis.  Remember that this is the genus with no notch in the "frontoclypeal apotome" (front edge of the head).

4. One of the many brushlegged mayflies.

5. And, the Baetis intercalaris small minnow mayfly (I found two, actually).

Remember that the key to identifying this species of Baetis is the presence of light-colored "parentheses marks" at the leading edge of the abdominal segments.    These are quite clear in the microscope photo below.

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