once you get the mixture right, they'll breed like nothing else. The mixture is tricky, too dry, and the larvae cannot eat it. Too moist and sticky, they canot move and will all die.
The NEXT problem is keeping enough of it in there. When deprived of food, the larvae go on a rampage in search of food. IF you have a couple dozen moths, you'll end up wiht many hundreds of baby worms - and they go through the food quickly. The next thing you know, all of the food was consumed, and they took off looking for more... all over the place. When they run out of energy, they pupate, even if they're tiny. I was picking off tiny itty bitty little cocoons from my closet walls (and all the boxes that were IN that closet)for 2 years afterwards...
Not to mention how annoying the tiny itty bitty moths that resulted were.