There are a wide variety of mayfly and stonefly nymphs that can look pretty similar.
Most (but not all) mayfly nymphs have three "tails." All stonefly nymphs have two tails. So a good rule of thumb is that if it has three tails, it's a mayfly, though this isn't foolproof. To definitively distinguish between mayfly and stonefly larvae, you almost need a magnifier to look at gill placement and the extremely tiny "claws" on the end of the legs, but that's tough to do in the field.
There is a small black stonefly that seems to hatch on the Caney in the winter and very early spring, but I've never seen it upriver from the Kirby Road access.
Mayflies are a little more common upriver, and last October there were a few respectable bluewing olive hatches within a mile or two of the dam, at least as far upriver as Lancaster. The mayflies are still not as thick as midges and blackflies in the upper 5 miles of river, but since the Corps started sluicing in low oxygen times and providing a minimum flow, the water quality improvements have allowed the mayfly population to expand upstream somewhat.
bd
Last edited by bd-; 08-12-2011 at 05:35 PM.
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