To confirm it was not just the caterpillars' chewing mechanism that was degrading the plastic, researchers "mashed up" some of the worms and smeared them on polyethylene bags, which achieved similar results.
"It's extremely, extremely exciting because breaking down plastic has proved so challenging," said Dr Paolo Bombelli from Cambridge University.
"If a single enzyme is responsible for this chemical process, its reproduction on a large scale using biotechnological methods should be achievable."
He said the most likely scenario was one whereby existing recycling plants could be adapted to biodegrade mass quantities of plastic using the enzyme or enzymes. But he added the enzymes could one day possibly be sprayed directly onto landfill sites or even infused into sea plants in order to degrade plastic already in the environment.
Polyethlylene is the most common plastic in the world and is primarily used for plastic bags and packaging.
The creatures transformed the polyethylene into an "unbonded" substance called ethylene glycoll.
Published in the journal Current Biology, the study says it is likely that digesting the beeswax found in hives involves breaking down similar types of chemical bonds. The beeswax on which the worms grow is composed of a rich diversity of compounds including fats, oils and some hormones.
Bertocchini, who led the research at CSIC, said: "We are planning to implement this finding into a viable way to get rid of plastic waste, working towards a solution to save our oceans, rivers, and all the environment from the unavoidable consequences of plastic accumulation." Bombelli said any initiatives to biodegrade plastic had to come alongside efforts to prevent the use of it in the first place.