Thursday, April 21, 2011

After the Flood: A Look at My Trib to the Moomans

                                      Just look at the ugly places I have to go to find insects (!)

The storm over the weekend dumped, I've been told, 5 inches of rain into the Moormans in Sugar Hollow.  The river flooded all three bridges that cross over the river as it makes its way down the valley.
So I didn't know what I might find today in my "hidden stream" (see previous entries) that steeply descends into the river below.

The water, even in this little stream, was still fast and high: still, I had no trouble finding insects -- this is very fertile water.  But I do think the flooding impacted what I was able to find.  To wit -- I did not find a whole lot of stoneflies: one Perlid (common stonefly) , two Perlodids, and two Peltoperlids (Roach-like stones).  All of these were in leaf packs, but that's not many nymphs given the number of leaf packs that I sorted through.  I suspect that, since leaf packs were clearly flushed from one place to another by the flow of the water, they have not yet been re-populated.  But there may be other ways to explain this.
Anyway, some photos.

1) Peltoperlid (This was a big one, close to 3/4" long.)

2) Perlodid (Isoperla similis)

You may notice that its left eye is missing!  I don't think I did this with my tweezers; I never pick up bugs by the head.  I guess that bad things can happen in nature.  Was it an accident?  Or did he run into a bigger stonefly?!

I actually found more insects on the rocks than I did in the leaf packs -- and that's rare.  Some rocks were covered with flatheaded mayflies, mostly genus Epeorus, but also a fair number of Leucrocutas and a few Maccaffertiums.   Down in the valleys, a lot of the Epeorus flatheads have already hatched: at this high elevation, there are some that are close to hatching -- but many that still need to grow.  Here's one in the pre-hatch stage with very dark wing pads.

I saw a few Ameletid mayflies -- but they're getting scarce.  Also on rocks, a lot of Uenoid case-maker caddisflies -- which surprised me.  In other streams that I visit, Uenoids are mostly now in pupation.  Again, that that is not yet occurring up here is probably due to elevation.  One of the Uenoids I found had a very nice case.  My photo's not great, but it will do.  The large stone chips on the sides of the case are characteristic of Uenoid construction.

And I found another "Northern Case-maker" (Limnephilidae) here, genus Pycnopsyche, the very same type of larva I found here last time.  I waited a long time for this bug to emerge from its case (the three-sided case made of leaf fragments), but it just wouldn't come out, even when a flathead sat on top of the case and a netspinner (genus Diplectrona) came by for a visit!

So I gave him a sip of alcohol from one of my vials, and he finally made an appearance.  In this photo, the "lateral humps" on the first abdominal segment that are characteristic of this caddisfly family are easy to see.  Remember they're used to stabalize the larva inside its case so it can move its abdomen up and down, generating a flow of water (for oxygen).

Finally, I also found some "Net-winged midges" on rocks.  This is the midge (Blephariceridae) that's very intolerant of stream impairment.  I took two photos, getting dorsal and ventral views.  You may recall that on the ventral side, this midge has little "suckers" that help it hold on to the rocks.   But there are also "gill tufts" on the segmented body -- something I've not seen before.  They're very clear in Voshell's illustration (J. Reese Voshell, Jr., A Guide to Common Freshwater Invertgebrates of North America, p. 171).



Addendum:  There were also quite a few spiny crawlers here -- but nothing like I've been seeing in other streams.  And, I picked up a couple of black flies: one was Prosimulium, the other was Simulium!

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