This is nature's way of cleaning up dead colonies. Send in the wax moth!
If it weren't for the wax moth (Galleria mellonella) the world would be full of comb - there is nothing else that eats it, except for the odd desperate mouse.
Sorry that this photo is out-of-focus. I should have removed my hood to take it.
This hive went queenless, despite my best efforts, and eventually all the bees died of old age.
Then the wax moth moves in. The larvae eat their way through the larval cases that the bees hatched from, leaving a disgusting mess of silk and faeces.
You can see the larval cases of the moth on top of the frames here.