yea man swt in hotwater cupboard, will only speed them up, on the other hand if u want to slow down ive heard of ppl storing mealworms in fridge BUT bringing them out once a week for upto a day just to rehydrate and feed them etc
also put a couple of layers of hessian or old sacking or 1 layer of that and abit of carpet ontop, keeps warmth in as bugs moving makes heat (i just use 2 layer hessiano now) feed out sliced carot/apple/spud etc between the layers just makes it cleaner all round & best of all it makes it easier to harvesto the mealio