This ravenous caterpillar is a global agricultural menace and a secret medical hero.

Nature · Published 3 October 2026 Swipe more like this →

In short: The fall armyworm is a destructive moth larva that can devastate entire fields overnight. While it causes billions in crop losses across the globe, its unique cellular structure has become an essential tool in modern medicine, powering the production of life-saving vaccines, including those for COVID-19 and influenza.

The fall armyworm (Spodoptera frugiperda) earns its name from its habit of moving in large, destructive groups, consuming over 80 different plant species. Native to the Americas, this moth cannot survive freezing temperatures, yet it has rapidly invaded Africa, Asia, and Australia. Its larvae are most destructive in their final stages, where they require 50 times more food than when they hatch. In extreme cases, they can destroy entire crops in a single night, leading to estimated annual maize losses of 17.7 million metric tons.

Beyond its reputation as a pest, the species is a fascinating subject for evolutionary biology. It appears to be undergoing sympatric speciation, diverging into two distinct strains—one preferring corn and the other rice—based on habitat and reproductive differences. These larvae also exhibit a puzzling behavior: cannibalism. While studies suggest this often decreases their own fitness, it may serve to remove competitors and secure resources in resource-scarce environments.

Paradoxically, the fall armyworm is a cornerstone of biomedical research. Scientists utilize Sf9 and Sf21 cell lines derived from the moth to express recombinant proteins using baculoviruses. This technology is critical for vaccine development; for instance, the Novavax COVID-19 vaccine relies on these infected cells to produce the SARS-CoV-2 spike protein. Similarly, Sanofi uses these cell lines to manufacture the trivalent influenza vaccine, Supemtek TIVr, highlighting how a creature that threatens global food security also plays a vital role in protecting human health.

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