This usually isn't the time of year that we are looking for hatches, unless you have midges on the brain. Fortunately there is a bug besides the midge that begins to hatch for us at the beginning of each year. I personally look forward to these bugs to get active each year. It is the winter stonefly.
Just like other stonefly nymphs, they love oxygen. This means that you will find more of these bugs in and around riffles of faster water where there is more oxygen. Usually the best nymphing to be had is along the soft edges of these runs and their tailouts. When these bugs start to get active in the bottom you can usually tell. The feed on small, black stonefly nymphs all of a sudden gets very good. Some days I'm fishing nothing else except two stonefly patterns, hoping for that rare double hook-up on one rod.
The bugs have an interesting 1 year life cycle and keeps them smaller sized, usually a quarter to half inch in length. In mid to late winter they begin to hatch into adults after crawling onto the bank or a nearby bridge. The adult stonefly has a very short life, they only live long enough to mate and drop eggs back into the river. This could be less than a day. Once a nymph has developed they are active in the river until late spring. These nymphs need cold, crisp water. Once the water temps rise enough they go dormant, almost hybernating, in the bottom until temps drop in the fall. When the water cools in fall they begin to feed again and do most of their growing before becoming an adult. Having such a short life span as an adult is probably the reason we miss spotting them.
These stoneflies can totally change winter fishing for you. If you are heading to a river soon that has summer stonefly hatches make sure you are ready for their winter cousins.
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