Polystyrene is a great packing material but it degrades only slowly in the environment. Organic waste such as food scraps disappear much faster because of the work of many insect scavengers. It should not be surprising that from the millions of insects some scavengers would be able to digest polystyrene.
Two species of tenebrionid beetles, the common mealworm Tenebrio molitor and the superworm, Zophobas morio have the ability to digest polystyrene. This ability to digest polystyrene and use it as a carbon source is rests with bacteria that reside in the beetle guts. The isolated bacteria have enzymes capable of digesting polystyrene. The bacteria need the moist environment of the beetle gut and the ability of the beetles to grind the polystyrene into tiny pieces to be successful.