if you really can't get him to eat anything other than worms, you might just want to bite the bullet and get an all winter supply from NY worms
you can keep them in a garage or basement in a large tub or a cooler
Cabelas sells a worm kit for anglers (no worms, but bedding and food), but you can just use a cheap styro box
the minimum order from NY worms is 500 . . .
where in NY are you?