I do incorporate a "trigger" in my nymphs but the "trigger" is not the pattern. While fishing late one evening, a mayfly hatch arrived and they were everywhere and I caught one and noticed that their head/eye had an orange pink tint to it plus there was a tint of it in the body. I guess it was not really a strong orange color and maybe a little orange/pink cast to it. I started using orange thread on my nymphs for the head. I would complete the fly and do a whip finish using whatever color thread I used for making the fly and then do another whip finish over the first one using orange thread. It may make no difference but I have more confidence when fishing them.