(I don't know where the bug feedback site is...) There is a bug where AI worms get stuck caterpillar crawling, and they don't target anything. They just bounce around the screen, only turning when they hit an obstacle. They can still eat things, but they won't target food. This is more common in max size worms, but can happen to ideal sized worms as well. If their segments are destroyed, they will speed up a bit, then slow down again. Doing this repeatedly can snap then out of their trance. They can return to normal before then, but they are easy food and will probably get eaten.
Some snap out of it, others become HOR' DOURVES.