Researchers from Virginia Tech, the University of Tennessee, and the University of Minnesota have identified a natural, polyester-based material produced by cellophane bees that possesses the unique ability to degrade in ordinary soil within months.
The findings, published November 2 in the Proceedings of the National Academy of Sciences, suggest that this insect-derived substance could serve as a model for developing sustainable, synthetic alternatives to conventional plastics.
Cellophane bees, or Colletes inaequalis, are solitary insects native to North America that construct underground nests. To protect their developing young, females secrete a liquid from a gland located near their stinger, which they spread across the walls of their nest chambers. This secretion hardens into a thin, translucent, and flexible film that researchers have long noted resembles plastic.
The material is composed of approximately three-quarters plastic and one-quarter silk. Chemically, the plastic component is a polyester that shares several features with polyethylene, including a similar crystal structure and degradation temperature. Polyethylene is a dominant force in the global plastics industry, accounting for roughly one-third of annual production—approximately 160 million tons—but its tendency to persist in the environment for centuries makes it a significant source of pollution.
The conventional wisdom is that it actually makes it harder to break down.
said lead author Jonathan Coote, an assistant professor of sustainable biomaterials at Virginia Tech, regarding the material’s semicrystalline structure and chemical cross-links.
But that is not what we see.
To track how the nest lining breaks down, the team collected samples of Colletes inaequalis nests from Tennessee sites between March 2023 and February 2024. The researchers retrieved the nest cells from depths of 7 to 12 inches underground.
The study revealed that the linings remained largely flexible and intact for the first four months. However, measurements showed a significant shift in composition: the polyester portion of the lining dropped from about 73% of the total weight to roughly 40% within that same four-month window.
By the seven-month mark, cracks had formed in the material, and within approximately one year, the linings crumbled upon handling. This rapid breakdown in ambient soil conditions contrasts sharply with many commercial bioplastics, which often require specialized industrial composting facilities to degrade.
While the bees’ nest lining is not currently a replacement for commercial packaging, the research team is investigating the molecular mechanisms behind its rapid degradation. Researchers are exploring whether the polymer chains’ mixed lengths or specific enzymatic pathways—such as the potential role of esterases—contribute to the material’s environmental clearance.
By identifying these natural design principles, scientists hope to engineer synthetic materials that maintain the physical strength and flexibility of polyethylene while ensuring they break down into harmless organic compounds after use.
This work aims to address the limitations of current market alternatives, which frequently force a trade-off between structural durability and environmental degradability. Scientists first reported that these bees produced a polyester in 1979, but the substance received little scientific attention for decades.