It looks like you have a fairly small dekay there so it may be a little intimidated by the bigger worms even if cut up? What you could do is the next time you go to feed him try and hunt down some slugs. I found when I had dekays they *never* turned down slugs. Also are you sure you are feeding him the right type of worms? They will not eat the little skinny worms that I usually found in my backyard, I had to go out to city island and buy some from the bait shops.