Nutria is the fur, Coypu is the animal (except in the US where the animal is also called Nutria). Coypu is a large, semi-aquatic rodent which is larger than a muskrat and smaller than a beaver.

The fur on these patches have the properties fly tyers expect: the under-fur is dense, is fine and fairly short, and the guard hairs are thicker, stiffer and longer. Cut a clump at the skin and pull out the guard. With a little rubbing the under fur quickly makes a fine, textured dubbing. From the natural-coloured patch the under fur is a rich grey-brown. It spins easily and dubs a small dry fly rather well.

All these patches are from tanned skins and Nutria seems to bleach and dye well, so the under fur and guard from bleached patches are brightly coloured. The texture and type of this fur means it does not soak easily, so, in my opinion, the under-fur is more suited to floating flies. However, the tanning process has removed any natural oils so inevitably this is less waterproof than truly natural fur but we can cure that with floatant.

The guard hair length runs up to 4 or 5 centimetres. Stacking a clump suggests there is just enough consistency to even the lengths but stacking means discarding rather a lot of shorter hair. On a fly, this guard is similar to squirrel tail, with a hint of bear. The texture of Nutria guard varies. The guard on some patches is fine, soft and easy to tie others have guard with a harder slightly coarser texture which is almost as slippery as squirrel tail. Clearly, the difference is down to where the patch comes from on the animal. All the patches are very useable and useful.

As a UK tyer, I would want the coloured patches more than the natural, and use bleached and dyed Nutria for salmon and sea trout flies in preference to bleached and dyed squirrel (which is both hard to get and, since bleaching tends to damage squirrel tail, often means damaged fragile hair and rather insipid colours).