Hi Mark,
Red wigglers are a very good food but nutritionally they look sparse at the surface since fed live. The really contain little protein mostly water 80+percent. They are about 10% protein . Very good for micro nutrients based on what you feed them. Just dont rely on them for a main food.
Details here in an excellent article...
http://bamboozoo.weebly.com/the-feeders--bugs.html
Hth,
Al