I think any grain will heat up your bin. I would be careful not to bury it. Instead, sprinkle on top and not more than 1" thick, as it will crust over and take out your air. It should also be dampened. I have a lot of plastic bins and have experience with doing all the wrong things..:) I do have some in-ground bins that I use grain "plugs" during winter, that act as little furnaces to keep the worms up and feeding.

Pocket feeding maybe okay if not too many bread crumbs, just make sure there are other pockets that are cool for the worms.

I find when I first feed a pocket (about 1 lb in a 6"x4" area) it heats up and then cools off after 3 days.

Although I did have problem with wheat germ (stinks and hot). Even smelt in my homemade compost tumbler.

Good luck.

I like the idea of "grain plugs" to keep the bin warm during the winter. I was thinking about moving the bin out to the garage (my bin is too small to leave outside during the winter - just a 10 gal Rubbermaid) - and using the grain to keep the bin warm would be great. The garage usually stays in the 40-50 range during the winter - with properly managed grain products, I'll bet I could have a nice cozy worm habitat over the winter! Thanks for the suggestions.