Can worms really eat plastic? Waxworms, the caterpillars of the greater wax moth, can chew through polyethylene bags in minutes, and research since 2017 shows they do more than shred it: substances in their saliva chemically attack the plastic. That is a genuine scientific discovery. It is not, at least not yet, a way to clear the world's plastic waste, and the difference matters.
This guide explains how a beekeeping accident turned into a line of research, what the experiments measured, why some scientists urged caution, what the 2022 saliva enzyme study added, and what the findings mean for anyone hoping biology will solve the plastic problem.
A beekeeping accident in Spain
The story begins with Federica Bertocchini, a developmental biologist at the Spanish National Research Council (CSIC) and an amateur beekeeper. While cleaning her hives she pulled out a number of waxworms, which are a well-known pest, and put them in an ordinary plastic shopping bag. When she came back, the bag was riddled with holes and the larvae were crawling free.
Waxworms are the larvae of Galleria mellonella, a moth found almost everywhere honeybees are kept. The caterpillars tunnel through honeycomb, feeding on wax, pollen and debris and lining their tunnels with silk, which can trap emerging bees. Beekeepers fight them with heat, cold or fumigation. Outside the hive, the larvae are bred in large numbers as live food for pet reptiles and as a laboratory model for studying infections and the immune system, where they can replace mammals in some tests.
Beeswax is a mixture of long hydrocarbon-rich molecules, and polyethylene, the plastic in most carrier bags, is also built from long chains of carbon and hydrogen. That chemical resemblance is why the escape from the bag caught a scientist's attention.
The 2017 experiment and what it measured
Bertocchini teamed up with Paolo Bombelli and Christopher Howe, biochemists at the University of Cambridge, and the three published their results in the journal Current Biology in 2017. They placed about 100 waxworms in a supermarket bag. Holes appeared within roughly 40 minutes, and after 12 hours the bag had lost about 92 milligrams of mass. For comparison, bacteria reported the previous year degraded polyethylene at around 0.13 milligrams a day.
Chewing alone could explain holes, so the team ran a second test. They mashed some larvae into a paste and spread it on polyethylene film. Holes appeared there too, which suggested that something in the worms' bodies, rather than their jaws, was breaking the material. Bombelli put it plainly at the time: "We showed that the polymer chains in polyethylene plastic are actually broken by the wax worms."
The researchers did not know what was responsible. They suggested an enzyme, perhaps from the salivary glands or from bacteria living in the gut, and proposed that if it could be identified, it might one day be produced on an industrial scale.
Why other scientists urged caution
The headlines that followed, about worms that could "save the planet", ran well ahead of the data. Several questions were open from the start.
First, it was unclear whether the larvae were eating plastic as food or just biting through it to escape. Bombelli himself noted that this mattered: an animal escaping a bag will soon stop, while one that can live on plastic might keep going. Second, mass loss and holes do not prove digestion. Critics, including a reply published in the same journal later that year, argued that the evidence did not yet show the worms were turning polyethylene into simpler molecules rather than altering or fragmenting it. Third, as marine chemist Christopher Reddy pointed out, any organism given plastic alongside tastier food is likely to prefer the food.
Researchers also debated the role of gut microbes. Work on a related insect, the Indian meal moth, isolated gut bacteria that can grow slowly on polyethylene in the lab, and for some years many scientists assumed microbes did most of the work in waxworms too.
The 2022 discovery: enzymes in waxworm saliva
In 2022, Bertocchini's group in Madrid published a study in Nature Communications that moved the story from observation to chemistry. They collected saliva from the larvae and applied it to polyethylene film at room temperature and neutral pH, with no heat or chemical pre-treatment of the plastic.
Within a few hours of repeated applications, spectroscopy showed that the plastic had been oxidised, the crucial first step that normally takes sunlight and heat months or years to achieve. The team detected small breakdown products, including ketones with 10 to 22 carbon atoms, and traced the activity to two proteins they named Demetra and Ceres, after Roman and Greek goddesses of agriculture. Demetra produced visible damage and breakdown products; Ceres oxidised the plastic without producing detectable by-products. Saliva from a different moth species had no effect.
The speed of the reaction led the authors to argue that gut bacteria alone are unlikely to explain what waxworms do. They were also careful about limits: the exact mechanism is not yet confirmed, each larva yields only a few microlitres of saliva, and one of the products detected was an antioxidant additive released from the plastic itself.
Why this is not a plastic cleanup crew
The scale of the problem helps explain why caution is still warranted. A widely cited 2017 analysis estimated that about 8.3 billion tonnes of plastic had been produced since the 1950s. Of the plastic that had become waste, only about 9 percent had been recycled and 12 percent incinerated, with the rest piling up in landfills or the natural environment. Another estimate suggested that between 4.8 and 12.7 million tonnes of plastic entered the sea in a single year.
Against numbers like these, a hundred caterpillars removing 92 milligrams in half a day is a laboratory curiosity. Releasing waxworms into landfills or the ocean is not a serious option: they are beehive pests, they cannot survive at sea, and nobody has shown they can live on plastic alone. Releasing genetically modified bacteria carrying waxworm genes would face strict regulation, and the same questions about measurement would apply.
The realistic hope is narrower. If enzymes such as Demetra can be produced and stabilised, they might one day be used in closed, controlled recycling plants to break down polyethylene that is hard to recycle by other means. For that to work, engineers would have to show how much plastic is actually converted, what comes out at the end, whether the products are safe or useful, and whether the process copes with dirty, mixed waste. None of that has yet been demonstrated at scale.
Common myths, and what actually helps now
Myth: worms will eat our landfills. No study has shown waxworms digesting plastic in the quantities or conditions found in real waste sites.
Myth: if something breaks plastic, the problem is solved. Breaking long chains into smaller pieces can create microplastics or release additives unless the process continues all the way to harmless or reusable products.
Myth: rich countries recycle their own plastic. For years, large amounts of plastic waste were shipped abroad, often to Asia. When China sharply restricted imports in 2017, much of that trade moved to other countries with weaker waste systems rather than disappearing.
Until enzyme recycling matures, the methods that work are familiar ones: using fewer single-use items, choosing products designed to be reused or refilled, keeping waste out of the environment through good collection, and backing local rules that cut unnecessary packaging. Plenty of towns and countries have already restricted plastic bags and straws, and reuse schemes are spreading.
The waxworm research remains worth following. It has revealed a natural ability to attack one of the toughest plastics at room temperature, something chemists had struggled to do. The best way to read it is as an early clue for future recycling technology, not as a reason to stop worrying about the bag in your hand.
Sources: Sanluis-Verdes, Colomer-Vidal et al., Nature Communications (2022): Wax worm saliva and the enzymes therein are the key to polyethylene degradation; Smithsonian Magazine on the 2017 Current Biology study; Wikipedia: Galleria mellonella; Wikipedia: Plastic pollution.
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