All You Need To Know About March Browns And Gray Foxes

 It was at least twenty years ago that Paul Weamer told me that March Browns and Gray Foxes had been reclassified as the same species. Maybe they are, but as fly fishermen you need to treat them differently. They are different sizes, different colors and hatch at different times although they do appear on the river during the same calendar period. 

The March Brown - For the first fifty-five years I fly-fished, this was one of the two best attractor flies for blind casting trout streams. Why? They are big (size 10/12). They taste good (trout love 'em). They take a long time to get off the water, and they hatch (sporadically or intermittently as trout fishermen like to say), all day long. In the past twenty years of fishing I have watched the March Brown dry fly turn into an afterthought, no more useful than a vestigial organ (it rarely leaves my fly box). How many March Brown duns have you seen eaten by trout in say the last five years?

Why? Drift boats and percentages. I'll try to explain. March Browns hatch all day long while many other may flies hatch in a shorter and far more concentrated period, (Gray Foxes for example hatch from 7:00pm until dark). Because of their day long hatching, fish are always looking for them. Guides know this and for years have had their sports outfitted with March Brown dries. With drift boats, no fish gets a free pass. All rising fish are cast to. Some river sections see over fifty boats in a single day. 

So, here is where the numbers come in. While the total number of March Browns that hatch in a day is substantial, you rarely see more than a handful on the water at once. The fish are hungry and always looking for them. When a fisherman sees a rise he immediately throws his March Brown to the fish. Within a day or two of the start of the March Brown hatch most every fish up and feeding on March Browns has been thrown at and most have been hooked. The fish learn quickly not to touch the duns. You still see big boils and some splashy rises but the fish are not eating duns. They are chasing the emerging nymphs in the water column. Throw your dun at today's boils and see what you get - ignored.

The Gray Fox - Is smaller than the March Brown with a lighter wing color and an under body (the side the fish see) that is grayish in color. Most importantly the Gray Fox hatch in a concentrated period from about 7:00 until dark. Why is this important? Because with a concentrated hatch, the odds of a fish getting hooked go down dramatically. There is positive reinforcement every time a fish eats a Gray Fox that doesn't have a hook in it. This doesn't mean a fish will eat your Gray Fox, but at least it's a possibility. The odds of having a fish eat your March Brown aren't much better than your chances of parlaying a twenty dollar bet into a million dollars before leaving the casino.