The necessary materials are cheap and It’a a sedge! The most spread imitation of this fly has green body, grey wings and red hackle easy to find: rabbit hair , feathers from the chest of duck, brown hackle and a 2xlong hook
If you like, you can add a thin tuft of grey CDC  when making the wing, or even use another color if you think it will work.
For the flies that are posted here I used Daiichi D21 #16 hook, thread 17/0, TLRD042 dubbing to imitate the sack of eggs of the insect and TLRD063 dubbing for the body. The wing is made of Mallard Bely and the hackle from a red rooster feather.
 

Hook : Daiichi D 21BL #16 ( 2xlong )

Thread: 17/0 Uni

Body: dubbing TLRD042 / dubbing TLRD063

Hackle: red

Wing: malard bely

Second Wing ( Under wing): CDC barbs - optional