Inside small plastic containers lined across lab benches in São Carlos, in the interior of São Paulo state, small green bodies quietly chew through what once seemed virtually indestructible. Long feared across Brazilian farm country for its appetite for crops, the caterpillar Helicoverpa armigera caught the attention of scientists at the Federal University of São Carlos (UFSCar) after it began gnawing through the lids of its own plastic enclosures in an effort to escape.

That accidental observation prompted a team led by Flavio Henrique Silva, a professor in the Department of Genetics and Evolution at UFSCar, to study the insect's digestive tract. Laboratory analyses revealed that the caterpillar's gut hosts fungi capable of breaking down expanded polystyrene, commonly known as styrofoam. Composed of 98 percent air and only 2 percent raw polymer, styrofoam is widely used as a thermal insulator and packaging cushion, yet its light weight and bulk make it expensive to collect and rarely profitable for standard recycling operations.

From agricultural pest to biological recycling

Historically classified as a damaging agricultural pest in Brazil, the species has long required intensive chemical controls in soybean, corn, and cotton fields. In the controlled environment of the university laboratory, researchers are now testing custom diets to determine how the gut microorganisms break down complex polymer bonds into reusable molecules.

Silva told TV Globo's Jornal Nacional that while the work remains in its laboratory stages, the findings offer a viable path for urban waste challenges:

In the future, we hope to achieve a degradation process that transforms the polymer into a reusable molecule, even if the breakdown is not complete. Everything we do is currently on a small laboratory scale, but the goal is to expand that. We observe natural phenomena and try to apply them in practice.

The industrial recycling sector has also expressed interest in the findings. According to Carla Castilho, a technical engineer at the Brazilian Plastic Industry Association (Abiplast), discarded styrofoam that cannot be processed by sorting machinery could eventually be directed toward biological degradation setups. The process shifts the role of the caterpillar, turning the persistent creature that once chewed through laboratory lids into an unlikely asset for managing urban plastic waste.