This is true. I used to breed and sell them in SA. When the worms were full size I would put them in fishing tackle boxes, the ones with lots of little compartments. Each one would go in their own compartment with no food or water. I would place the tackle box with worms in a heated box. They would start to pupate within a week. It is almost as if they have to get to a point where they realise that there is nothing left to live for or do in there worm form and are forced in to the next stage of the cycle. The beetles are huge!