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I was out late last week, at the local rapids, too hot and humid to work around the place. I was having a bit of fun with the smallies and fallfish using prince nymphs and zug bugs. Then about an hour before dark I noticed a flight of large mayflies. The action picked right up with fish rising all around, I switched to the largest adams I had and had a ball with all the surface action. I've seen mayflies before, but being new to fly fishing, I'm paying more attention now. It is very interesting to see the ecosystem in action. I did some online research and I believe the mayflies were Hexagenia Atrocaudata. I suppose now I'll to have monitor and try to predict these hatches and cash in.

Match the Hatch....

I went out fishing once this summer after a local mayfly hatch.... Me and some others had nothing to match the hatch so the fishing was pretty dismal.

If it was a Hex hatch it is definitely a late hatch as they're usually finished by early August. In any case, #6 Stimulators are always good to have in your box for just such situations. This time of year you're more likely to encounter an Iso hatch, which is just a good.

The fast water smallmouth in this area seem to key in on the mayflies. As posted earlier had success with prince nymphs and zug bugs. This evening I started out with a crayfish pattern and had a bit of success but thought I could do better. So I switched to a # 6 Muddler with a #12 BH Hares Ears dropper caught 4 bass right quick. Then lost that rig to a snag. So i put on black wolly bugger with a # 10 BH Pheasant Tail and caught a dozen more. They ranged in size from 3/4 to 1 1/2 lbs all fish were caught on the Nymph droppers. I would cast cross current let them dead drift then swing then strip in most takes on the drift. Its fun when you get 2 or 3 on consecutive drifts.

Do you think I can count on this hatch happening again this year, same place, same time? I hoping I can have another crack at them. I'd also like to determine if they are Mahogony duns or big slate drakes.

swampsinger wrote:Do you think I can count on this hatch happening again this year, same place, same time? I hoping I can have another crack at them. I'd also like to determine if they are Mahogony duns or big slate drakes.

In this case they are the same mayfly. Both of those are localized names. Better off referencing the scientific name Isonychia when looking for information. Dosen't really matter though just remember to fish a #10-12 grayish fly in September. It actually has a dark brown body/slate grey wings and one species has chartreuse forelegs. It's the last big mayfly of the season. The nymph is an inch long, very dark brown and swims like a minnow.

The only other late season mayfly are Blue Wing Olives they're usually later in the season but I don't think bass would be interested in those as they're very small and by the time they emerge the water will be cold.

The fly hatches likely won't be very good this fall because of the drought and warm water.

Every couple of years the mayfly hatch in Ottawa is so huge that it actually screws up fishing! Your one tiny fly gets lost among the thousands that litter the surface of the river and the fish are so bloated from eating them that it actually gets hard to entice a bite!

Thankfully this wasn't one of those years.

I was referencing the Otawa Fly Fishers hatch chart they listed the Mahogany Dun as Isonychia and the Big slate drake as Hexigenia Atrocaudata.Here loccally, in the spring there were clouds of the Brown Drakes. The Third evening as the browns were diminishing I saw some sulphers, this past week I saw a single large white mayfly not sure what type. I suppose you pay a lot more attention to these things when your fly fishing. Maybe its just me, but the wildlife seems a lot friendlier. I think when I'm wading to a foot or so above my arse I don't show the same silhouette. The muskrats, mink, herons, and water snakes are a lot closer than when I was standing on shore. One evening a yearling doe got in oposite and crossed right over to my side before it realized something was different.

A local river also has a heathy population of bass sized stone flies. I found these casings under the bridge.

I did more online snooping. Yeah, seems common or local names are all over the map. You could probably make a case for swicthing the common names on these two. Looking at the Isonychia dun, you can see where they got concept and name for the Leadwing coachman.

The may fies are back in the same location. I caught a couple and I think they are late hex or hexagenia atrocaudata. I went on troutnut.com seems thats what they are.
I compared by size and dark edging on both sets of wings.
ps The smallies were hammering a large nymph pattern.

This is the nymph I'm using. Its almost neutral bouyancy, with the bead head and foam body, in slow currents it drifts and rests on the bottom vertically, to imitate the burrowing nymphs.