Wednesday, May 16, 2012

And They're Just Out There Crawling Around in Our Streams: Maturing Eccoptura Xanthenses

I just made a quick trip to the Whippoorwill Branch of the Mechums, hoping to find some Stenacron flatheaded mayflies.  Did not see a one.  But I found this beautiful Perlid (common) stonefly, Eccoptura Xanthenses.   I couldn't resist taking and posting some photos.  The colors are unusual.  Almost all Eccoptura nymphs that I see, especially when they're mature, are fairly yellow with brown and black accents.  This one was more orange and brown.  Some photos for you to enjoy.

And this one, where our stonefly is perched atop a Northern case-maker caddis.

Now this is what mature Eccoptura Perlids normally look like:

Whippoorwill Branch is a very small stream, maybe 10 ft. across at the widest.  But in small streams like this you'll probably see more Eccoptura Perlids than any other genus or species.  This is the habitat that they prefer.  And they're maturing right now, the big transformation into terrestrial insects -- for most of these nymphs -- taking place in June and July.  In the mix of branches and leaves (submerged) that I looked in today, I probably saw 20-30 Eccoptura nymphs.  Most of them -- like the two in the photos above -- were getting ready to hatch, but I also saw some small ones.  Next year's crop.  Like most of the Perlids, Eccoptura xanthenses nymphs are "semivoltine," taking two years to go from egg to adult.

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