Dobsonflies and Hellgrammites for bait

My great grandfather co-authored a book called Bait Fisherman's Guide. I can always recall reading about the Hellgrammite and Dobsonfly in the book. Was even lucky enough as a young kid to meet and have Harold Ensley sign a copy for me (only real connection between Harold and the book is fishing but I wanted it signed for some reason). Anyway before I stray too much off topic, the dobsonfly and hellgrammite was simply flat out too cool to a young kid. Other bugs seemed pretty boring and small but not these they were massive and had large pinchers. For those noticing a connection, yes, I named my boat in honor of my great grandfather and his book detailing some information on dobsonflies.

So, I have been on the hunt for both to use as bait. For those of you that may not already know, the Hellgrammite is the larval stage of the Dobsonfly. They live for a few years as a hellgrammite and only around a week as a dobsonfly. I was lucky enough this year to have caught a few hellgramites and one dobsonfly recently. While fishing in general seemed poor the days I have used them as bait, I was at least able to get bites on them but failed to get a hook into something.

This early memory, has now inspired me to investigate more into hellgrammites and dobsonflies. Most importantly for others and myself "How good are they for bait?" "What is the best way to fish with them?" "What are the best ways to catch them and when?". If you have any stories or recommendations please post and I will do the same.

Never used the dobsonfly, but used the hellgrammite. They are plentiful in our area and will catch anything.
The way we fish them is usually with a very small splitshot, and drift them like you would a worm. Deeper water, more weight. I prefer to use a flyrod on smaller streams.
There's 2 little "feet" on the very back that some guys cut off. Also hook them from the beginning of the front of the collar, just sliding the hook under the collar, and out through the collar. Don't insert the hook too deep.
DON"T get bit by a big one, it will draw blood!
We always use a piece of screen secured between two sticks, with long enough sticks to have handles sticking above the screen. Find a shallow riffle, one guy holds the screen against the bottom while the other guy goes upriver maby 8-10', and gently lifts up rocks (some will hang on and can be picked off) and then shuffles the bottom with his feet as he works toward the screen. Keep doing this until you have enough to fish with.
I know that at some places, you can go right along the shoreline at a riffle, flip over rocks, and find them.