Worm composting, why are the worms trying to escape?

Yes, bedding is very important. Someone I knew once had a problem with all his worms trying to get out. When I got through all the questioning, I found out he thought it was a good idea that his worms should live in "soil". So he went out and bought bagged soil that stated it was ammended. He thought he would treat his worms to the expensive soil. Turns out it had added miracle gro type fertilizer in it that was burning the worms. The only worms that lived were the ones that got out while the getting was good.

I use peat moss / coir with shredded newspaper / straw / brown leaves mixed in. Supposedly composted horse bedding or composted manure is excellent if you live somewhere where you can find that. I live in the big city so I have to buy whatever I use plus there aren't any horses around here.

Oh, I also always cover the top of the bedding with leaves or old grass clippings and then with a thin layer of flat newspaper or cardboard. I have never used a lid and my worms have never tried to flee. You always find a lot of them in that top layer of leaves news paper though. My worm bin is a 38 gallon rubbermaid bin that I keep in my garage.