I have never seen any of these mealworms move. That's because they're dead. My crabs eat them up and love them. However, if you feed them after midnight, or you get them wet, bad things happen.
For instance, I tried to pick up a wet mealworm once, with my hand. It felt icky. The wormflesh felt alive, even though the worm itself was dead. I think my crabs had performed some sort of necromantic ritual on the mealworms, but I put the kibosh on that jazz fast, because I don't want no undead mealworms creeping around my house.