This is just the ticket for back-end olive hatches, when a size 14-16 hook with an olive-dubbed abdomen imitates that of the large dark olive. One tied on a size 18 hook with Orvis Superfine No.12 (Pale Morning Dun) is a good imitation of late-season pale wateries.
Material list for the Olive CDC
Hook: Size 14-18 Mustad R50
Thread: Tan 14/0
Tail: Dun cock hackle fibres
Abdomen: Wapsi Superfine dubbing No.14, olive
Wing: Natural CDC
Thorax: SLF MC Finesse No.1, brown-olive