Isonychia Mayflies

[Adam Grace]

I have always wanted t fish the isonychia hatch on the Pit River because of the feeding frenzy these large mayfly nymphs can prodduce, unfortunately I have never fished it nor have I seen the mayfly nymph or dun before my recent trip to the Trinity river.

There were tons of shucks littering the rocks by the banks.

http://img.photobucket.com/albums/v238/flyguyag/fishing/IMGP0176.jpg


Here's a picture with a fly right next to what it can represent.

http://img.photobucket.com/albums/v238/flyguyag/fishing/IMGP0182.jpg

I was even lucky enought o get a picture of their elusive adult stage mayfly better known as a Dun.

http://img.photobucket.com/albums/v238/flyguyag/fishing/isonychiaduncropped.jpg

I cropped my original picture to show the maylfy a little closer. The sun resricted how close my camera could get to the insect. Iwould have blocked out light if I got much closer. Please excuse the slight pixelation.

I hope you guys enjoyed seeing these mayfly pictures.

[Kevin Goding]

Yeah they are pretty rare, the only place I've ever caught em sampling streams was in Butte Creek up near Chico.

[Dan LeCount]

The Pit can have a nice Iso hatch some years :)

[neonymph]

I was getting ready to tie some, then further reading led me to believe they were mostly eastern flies. So, i didn't tie any. This renews my interest. If they are on the Pit, would you think them to be on the Fall River?

[DPLee]

"One notable species of mayfly is Isonychia velma, called the Great Mahogany Mayfly, that emerge in the fall on the Klamath and Rogue river watersheds. The nymphs are agile, swift swimmers and feed on tiny larvae and nymphs as well as detritus and algae. They are large and range from 12 to 16 mm and are brownish black with a distinct whitish mid-dorsal stripe. The gills are oval and plate-like and located on the first seven abdominal segments. Their three tails are heavily fringed on both sides of the middle tail and on the inner sides of the two outer tails. The adults usually hatch in late afternoon or evening, and heavy emergences often occur on cloudy or rainy days. Typically the nymphs migrate to the shoreline near riffle areas and crawl out of the water to emerge. Some of the nymphs may emerge in the surface film and a good number of the duns may be blown back into the river by wind gusts. The duns have slate-gray wings and dark-brown bodies with purple or olive highlights and are easy to recognize."

From – Half Pounder Steelhead, Life History and Fly Fishing by DP Lee, to be published spring-summer 2011.

[Larry S]

DP:
The isos are one of the main hatches on Michigan's AuSable during Aug and Sept.
Also, one of the isos has perhaps the neatest common name of any of the
mayflies --the white gloved howdy! When I fish back there, most of the time I
fish with an iso nymph as a dropper.
Look forward to seeing your book. Good luck with it.
Larry S