I use a small refrig. in the garage. I keep the temp around mid 40s.
One thing I have noticed is not to over feed them. If you do you must keep changing your bedding.I like to use a paper bedding that already has the feed in it.
I keep around 500 to 200 crawlers with no problems if i change the bedding every three weeks or so. One Big Plus to paper bedding is that it keeps your boat and hands nice and clean