Catgut is a great fly tying material for making nice flies with realistic aspect.If you are interested in catgut, you can find more info here.
Caddis pupae is one of the most effective flies for trout and grayling in Spring and Summer fishing time.
Here is the step by step:
Hook: Maruto Dohitomi C46WBL #12
Thread: Textreme Standard 6/0 thread-black color
Body Thread: Devaux yellow body thread
Body: Catgut – natural
Gills: White rabbit dubbing
Legs: Partridge hackle
Torax: Mad Rabbit Dubbing – natural and rust mixed
Bead: Tungsten bead – gold color