My worms always stay in the dirt, but I have a lot of them. I get a decent amount of mites so I flood the container and pour it out to get rid of them.
What I have discovered is after about an hour of disposing of the mites the worms all come to the top and all over the sides of the container to get out of the saturated soil. I then harvest them off the sides, and throw a little more dirt in to dry things up some.
I'm still using the bread/yogurt/yeast method.
I'll have to try some of the other methods recommended on here.
I've heard the catfood works great, but do you think it would limit some of the nutritional value of the worms? I thought the idea of the mixture was to essentially turn the worms into a Probiotic for the fish.