Every larva preserved in mezcal bottles tested by researchers turned out to be the caterpillar of a single moth species.
Genetic analysis settled a decades-old debate about the worm’s identity
Scientists from the Florida Museum’s McGuire Center for Lepidoptera and Biodiversity collected 18 specimens from various mezcal brands in Oaxaca, Mexico, in 2022. After extracting DNA, they found every usable sample matched the agave redworm moth (Comadia redtenbacheri). Morphological review of specimens with degraded DNA also pointed to the same species. This contradicts earlier assumptions that multiple insect types — such as weevils or skipper butterflies — might be involved. The study, published in 2023 in PeerJ Life & Environment, concluded the so-called worm is not a random assortment but a consistent biological entity.
The tradition of adding larvae to bottles began less than a century ago
Even though mezcal production dates back centuries in Mexico, placing gusanos de maguey in bottles started only in the 1940s. The practice was likely a marketing tactic to differentiate certain brands in a growing market. Over time, the larva became a cultural symbol, reinforcing perceptions of authenticity and exoticism. Yet its biological specificity was never verified until now. The long-held belief that the “worm” varied by region or producer has been undermined by genetic uniformity across samples.
Producers may face pressure to clarify labeling or discontinue the practice
Consumers who associate the larva with tradition or terroir might feel misled to learn it is not a wild harvest of diverse insects but a single farmed or collected species. Although the finding does not affect the safety or taste of mezcal, it could influence branding decisions. Some distilleries may choose to highlight the larval origin more transparently, while others could drop the practice to avoid perceptions of gimmickry. Regulatory or labeling changes are not implied by the study, but the discovery adds a layer of scrutiny to a long-standing marketing convention.
Is the mezcal worm safe to eat?
The study did not assess safety, but the larva is preserved in alcohol and has been consumed for decades without reported health issues tied to its identity.
Does this indicate all mezcal bottles contain a larva?
No. The researchers noted that most mezcal is sold without added larvae; only a small subset of brands include the gusano as a novelty or marketing element.
