The Slit Dwelling Burrowers Families Ephemeridae, Potamanthidae and Polymitarcyidae
The first thing that should be said about the three species of mayfly I chose to research is that both The Hex, and the White Fly are both excluded from the hatch chart I’ve been using and the reason for that is that in this area The Hex and White Fly produce substantial hatch numbers but in the warmer areas of the Mississippi River and the waters flowing into the river. As a result these two will most likely not be trout fly options but I am planning on trying to find these hatches next year and fish for bass or panfish willing to take the large flies.
With that said the burrowers can be found by sifting through the silt in the stream. With the flowing water easily able to sweep the nymphs through your fingers Hatches 2 suggests bringing a jar that you can fill and shake to stir up the contents to find the nymphs. Burrowers are easily identified by the two large tusks on the head of the nymph. Looking at photo’s one can clearly see the difference between nymphs with and without the tusks.
The Hex (Hexagenia limbata) 6-8 4x Long Tan-Dark Brown Late June-July
The nymphs and indeed duns of the Hexagenia are among the largest of the Mayflies. Note the hook size recommended for the duns of the Hex in 6-8 4x long. What I know of these for this area is that they tend to emerge only on parts of the Mississippi and that a friend of mine fishes this hatch on the river for all kinds of warmer water fish. Hatches 2 gives one hint as to how to distinguish Hexagenia from other burrowers. The other burrowers tend to have deeply forked tusks while Hexagenia have longer more rounded tusks. The main reason I believe that this is not a source of trout food is that the Mississippi has a better substrate that can allow them to have their U-shaped burrows in 3-6 inches of frim silt.
Yellow Drake (Anthopotamus distinctus) 10-12 Creamy yellow Late June-Early August
Hatches 2 has this species identified as Potamanthus distinctus. Looking at the nymphs of this species one can easily identify them by the gills that line both sides of the abdomen of the nymph. They are very long and have bristles spanning the distance between them. Tying these nymphs one might consider using very short ginger hackle to represent the gills on the sides, perhaps trimming the top and bottom feathers leaving only the sides. Hatches 2 suggests using a Light Cahill dry pattern in size 10.
White Fly (Ephoron leukon) 8-12 2x Long White Late August-Sept.
The white fly is most likely not going to be a large part of my fly box but I have heard whispers referring to the Ephoron Leukon and in my efforts to be prepared for next year I will not over look this genus of Mayfly. These white mayflies will emerge just after dusk in August and September. On my Dusk til Dawn run near the end of a long day on the water I watched what I thought at first was Ephoron leukon but turned out to be a white caddis fly. Hatches 2 has little to say about this species but all the more reason for me to try and find it next season.