Ken is right on when it comes to crayfish on the Kank. When the water clarity is there you can walk out and literally see the crayfish scattering in your path it's amazing. I wonder since the helgies seem to desire the area underneath the larger rocks on the Kank that this may have something to do with it besides the quality of water. Although I believe it ultimately does have to do with water quality I've noticed that perhaps the size rocks that inhabit the Fox aren't as large as alot of those that line the Kank. Maybe there isn't enough habitat as well.
I know that Case makes artificial helgies and you would in the past be able to pick them up at Batavia Tackle. Unfortunately I was over in that area this past weekend and that store is closed for business. Sucks.
You probably could find them at Angelo's in Wilmington or maybe BPS?? I'm not sure. Of course if you go online and do a search and find them here:
http://www.caseplastics.com/Products/Hellgrammite.htm
I've bought a few back in the day but never fished them with confidence. I know others do pretty well with the whole helgie or even by just busting off the tail and fishing them on a light jig. I'd rather stick to my jig and twister....I feel it has more action in the lure and better results.
If they were more accessible I'd probably use softshell crayfish above all. Unfortunately I'm not ready to drop 6 bucks on half dozen. I've gone out and seined them before but it can be tough to gather a fair number since they molt in a short period of time. I bet if I seined on the Kank I'd have more luck since the crayfish are so prolific down there. Smallies love those softshell for sure. Same with the channel cats.
Now where did I put that sein.....