Old Man-- I'm not Fred, but he might not come back to this thread because of the above post--don't know what got into THAT guy's head, but...

I'll try to answer your questions based on the little bit Fred and I have discussed about the Otis Bug through e-mail. I'm certainly not an authority on this fly, but I didn't want you to feel forgotten.

The flies Fred sent me are tied on long-shank #2 and #4 hooks, not salmon hooks, but I doubt that it makes a big difference. Chenille sizes vary with the size of hook and the intent of the tyer. If you want something to work in low, clear, water-- then smaller and dark would probably be best.

Weight is optional according to the water you fish, but the Otis Bug is designed, I think, to be fished low and slow, crawled across the bottom-- probably like a stonefly nymph. So body weight is probably a good idea. So is a beadhead, if you look at the Bugs in the attachment Fred linked to an earlier post.

The rubber legs and tails are made from living rubber, and I'm thinking that the round rubber now sold in the catalogs is what is in the picture from the Rogue Fly Fishers.

I'm guessing that the bug is an outgrowth on an old trout pattern, the Girdle Bug. This fly was tied about the same way that the Otis Bug is with legs and tails of rubber. But when I was going to college in Montana in the early '70s, the rubber was stripped from elastic waistbands on underwear, hence the "Girdle." The fly was intended to imitate a stonefly nymph, although imitate is a pretty strong word. The chenille on that pattern was a black-and-yellow variegated.