Red Annelids are a very important and common food source for trout in almost every river in the world. In many rivers like my local river (The San Juan River) trout will gorge themselves on these small yet high protein worms. This means that using flies that mimic them will yield high results.
The red hook is a popular hook for mimicking these red annelids. You can literally just fish the hook, without anything on it. Many guides do this because their clients loose so many flies, it makes short work of loading their boxes with annelid patterns. And it hurts less when they are lost. However, we who love to tie flies have some other options of this popular fly. Including this one, which uses some micro tubing for ribbing and a black head.
Here is the list of materials I used on the fly.
Hook: Daiitchi 1273 in size 20
Thread: Veevus 14/0 in black
Wrap: Micro Tubing in Yellow
Head Cement: Bone Dry UV Curing Resin