Just for your info...
There is a forum devoted to SFGing. If you don't get a response here, you might try posting your question there also.
I don't have a SFG - so can't help you there. Sorry!

I don't have worms in my sfg like I do in my regular garden spot. I guess this has to do with the fact that the regular spot has been worked on for 3 years, and is loaded with compost and hay. Lots of activity there. The sfg is only a year old, and in a different location, so it may need more time to get as much activity as the other location.

So since you built the sfg on you garden spot, then I would guess that you will have worm activity soon in your sfg. The only factor that will make them leave the top sections is the cooler weather, as the temps drop, the heat level in the raised part will drop more than below the surface ares.

The only ways I can think of to keep moles out, will also limit your worm activity. I've heard that getting a dog that stays outside helps control the moles. That option won't bother the worms.

Thanks people but I also have an irrigation system in place and it would be a real pain in the butt to have to install hardware cloth underneath. I do not see any signs of moles (they are moles) in the SFGs. The evidence is in the pathways under the mulch, but I think they are getting many of the worms, especially the NCs.

John

Here is a link that might be useful: Johns Journal