The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.
This one was surprisingly straightforward to identify. The lack of a sclerite at the base of the lateral hump narrows the field quite a bit, and the other options followed fairly obvious characteristics to Clostoeca, which only has one species, Clostoeca disjuncta.
Al514 on Sep 17, 2007September 17th, 2007, 2:29 pm EDT
What is the biggest mayfly species in the North East? I was at a 7 to 8 acre pond tonight that holds some nice trout, and I swear I saw some spinners about size 8 or 6! I had to do a double-take to make sure it was a mayfly! I didnt have my camera, so no pictures but Ill try and get some soon. It looked dark brown and around 2, possibly 3 inches in length.
Taxon on Sep 17, 2007September 17th, 2007, 3:45 pm EDT
There are only three mayfly genera with really large mayflies, which I would describe as being in excess of 1" in length, as measured from the front of head to end of abdomen, exclusive of tails.
These are Ephemera, Hexagenia, and Litobrancha, all burrowers in family Ephemeridae. Of those three genera, only Hexagenia are found in ponds.
Troutnut on Sep 17, 2007September 17th, 2007, 7:17 pm EDT
At this time of year, it was probably a different species of Hex, like Hexagenia atrocaudata. Check out the pics of that one on this site and see if they match a little closer still.
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist