Theres a guy on another site that uses a rubberband and a beadhead that a lot of people claim is effective.
I just use a cream colored caddis larva, which is what you'll be truly imitating in the water since wax worms don't live in water. It's been pretty effective for me.
No matter how exact looking a fly is to a wax worm it is not nearly as effective I guarantee. Make all the patterns you want but they just will not work as often as you think they should. I believe the majority of the wax worms success is the sent it leaves off. I took a few kids from school to help stock and then we fished for fish and I wanted them to catch fish. I gave them all wax worms and everyone caught fish while everyone else around wasn't catching anything.
I would have to disagree, i was fishing a pattern of a wax worm as pictured above right next to a bait fisherman who was fishing the real thing. I was catching fish, he was not, perhaps it was presentation.