I use white tying thread or rod building thread for my stripe.
When it gets wet it turns semi transulcent -- kinda that dull color like the natural.
Mute,
just for you to try, if you wish...
Use black poly propelene, fairly thick, for the wing case. It has some air trapping abilities and gives a flashback type appearence without sacrificing a thick dark wing case; and there is great contrast then with the white stripe. (make sure it is pulled really tight)