I have to set the record straight here. In my 9+ years of worm bin composting my bins have been through every experience from the best to the worst. My worms tell me that even though they don’t like being disturbed; they much prefer an environment that is loose and well aerated to that which is compact and dense.
Yes, I will agree that the worms do move through the bedding stirring it up, but you have to realize they are taking a very coarse material and breaking it down into a much finer material. In doing so the material is going to settle and become compacted. The worms are going to benefit greatly by being turned and loosened, incorporating air into the mix. Believe me the worms are happier. Add your fresh bedding and food stock at this time and the worms are going to reward you by actively moving into your fresh offering and getting right to work.
I supplement my feed with Purina Earthworm Chow. The directions on this professional product read as follows: “For best results, stir or turn the bedding at least twice a week. Keep the bedding loose and well aerated.”
Now I don’t turn my worms that often. My personal goal is to turn each worm bin at least once a month. Sometimes, especially during the winter months it just doesn’t happen. But during the worms’ active months I try harder. I know they are happier and more productive, which makes me be more productive.
My worms tell me they are happy. And now I need to get out and turn a worm bin.

This is the tool I use to turn my worm bins.
Happy Worming,
Christy
Mother Earths Farm
VermiCulture Northwest