The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.
This one seems to lead to Couplet 35 of the Key to Genera of Perlodidae Nymphs and the genus Isoperla, but I'm skeptical that's correct based on the general look. I need to get it under the microscope to review several choices in the key, and it'll probably end up a different Perlodidae.
Hellgrammites are the vicious larvae of the Dobsonflies, some of the only trout stream insects which pose a biting threat to the angler. The pincers of the adult are even more frightening that the larva's, and they're aggressive enough to use them once in a while.
This family's life cycle does not create good dry fly opportunities, but the larvae may be eaten by trout year-round. They are a secret told only by stomach samples of well-fed trout.
Cougmantx on Mar 9, 2008March 9th, 2008, 8:50 am EDT
Often times in March and April on the Colorado River north of Lake Buchanan in the Texas hill country, I will catch a bunch of Hellgrammies and fish them on a drifting line with a small split shot for channel cats. While I release most of them, often times I am stopped and asked what I caught them on. Since some of these fish will be in the 5 to 10 lb range it catches peoples eye. Their great bait for a channels, in swift water and clear rivers.
What really brings me to the area during these months is the White Bass and Stripper runs up the same river for spawn. I do alot of flyfishing for them. What brought me to this web site was trying to find a hellgrammite pattern that I might use to catch the channel cats when the bass fishing slows.
Chris_3g on Mar 9, 2008March 9th, 2008, 3:09 pm EDT
I think a lot of people use woolly buggers to imitate Hellgrammites. Instead of chenille, you could try wrapping the shank with marabou and giving it a bad haircut. Just a thought.
Hellgramite patterns can be simple or rather complex....here's one that I found on a steelhead site which I frequent. The wiggle-nymph style adds great action. Good Luck!
http://www.salmoncrazy.com/vforums/showthread.php?p=136651#post136651