Has anyone used the dark turkey tail fibers for nymph bodies. They seem to be more sturdy than pheasant tail fibers. Are there any other uses for them besides wing cases for nymphs?
You can wrap the fibers just like pheasant tail. Coat them in a flexible fixative and you can use them for down wing caddis and stoneflies. A lot of hopper patterns use them like letort hopper and Dave's hopper. Muddler minnows. You can take a single fiber and use it for ribbing. I'm sure you could even use them for dry and wet fly wings if you have a pair.
I've used them instead of pheasant tail fibers. They look nice but are even less durable than the PT fibers IMO. Make sure you rib with something. HA's sulphur is really nice example. Black ribbing of some type.
I do use wild turkey for many flies. Using it for wing cases and also wrappint it on. HA that's a really great sulpher nymph. Can I ask what the thorax is?
Be sure not to use as many fibers IMO they get bullky pretty quick. They do make pretty nice Caddis patterns as well and because of their length can allow you to make larger flies with them.
To answer the OPs question, I use dark turkey for a lot of things. I've found that the outside two tail feathers on a full tail have biots? that are pretty wide. I dye and use these biots? to make a deadly compara spinner pattern to imitate several different mayflies. They work great.