Tuesday, April 24, 2012

詢 (or 訪) 不遇 ("Looking for..but not finding"): a Trip to the Powells

A number of Tang dynasty (roughly 600-900 AD) poets wrote on a theme called xun (or fang) bu yu  (or ) 不遇 -- "looking for X (often the name of a recluse) but not finding him home."  I'm often reminded of those poems when I make my trips to the streams.  Today I went to Powells Creek in Crozet where I was "looking for" -- and expecting to see -- various small minnow mayflies and genus Neoperla common stoneflies.  Neither was "home"!  But I did find things that I wasn't expecting to encounter.

Above, a pretty mature common stonefly, Eccoptura xanthenses.  Beautiful colors, fully shaped/arced wing pads, and note how tergites 8-10 have turned black.  Like the Acroneuria abnormis that we saw last week, this common stonefly will be hatching in June or July.

I wasn't really surprised to see E. xanthenses: this is a species I usually see when I come to this stream.  But I did have three surprises.

1. I found two, fully mature Diploperla duplicata Perlodid stoneflies.  This is the largest of the two (11-12 mm).

This is a nymph we've been seeing all winter and spring -- and I've seen a lot of them lately in a number of streams.  All in all, it's a pretty drab insect compared with the many spectacular Perlodid stoneflies we find.  But, when they mature, they exhibit very rich colors and patterns.

2. Surprise number 2: Among the millions (well, a bit of an exaggeration!) of spiny crawlers on the leaves and the rocks-- they all appeared to be E. dorotheas -- was one spiny that we don't see all that often -- genus Eurylophella.

This is the type of spiny that has a large gill on tergite 4 that essentially blocks the gills on 5-7 from view.

I think this is only the fourth Eurylophella I've seen since I started taking pictures of aquatic insects, so I've not yet worked on identifying these spinys to the level of species.  Work to do on a rainy day.

3. And surprise number 3: Coming in second to the spiny crawler today in terms of sheer numbers -- the Perlodid stonefly Isoperla holochlora.

True, I'm seeing them now in a lot of the streams I explore, but I picked up 20-30 nymphs today (all returned to the stream) without looking real hard.  And, note that in Powells Creek, the I. holochloras have begun to mature.  Note how the rear wing pads are starting to flare out from the body.

Small minnow mayflies and Neoperla Perlids?  Just have to find them next time!

No comments:

Post a Comment