Scientists have confirmed that the larvae found in mezcal bottles, commonly known as “worms,” are not worms at all but the caterpillars of a single moth species, Comadia redtenbacheri, according to DNA analysis published in 2023.
DNA testing revealed consistent species identification across samples
Researchers from the Florida Museum’s McGuire Center for Lepidoptera and Biodiversity analyzed genetic material from 18 specimens collected from various mezcal brands in Oaxaca, Mexico, in 2022. Every larva that yielded usable DNA matched the agave redworm moth, and specimens without usable DNA were morphologically identified as the same species.
Findings challenge long-held assumptions about larval diversity
The results contradicted expectations that the larvae would represent multiple species due to wild harvesting practices and variations in appearance. Earlier assumptions had suggested the larvae could be moths, butterflies, or weevils, with the tequila giant skipper (Aegiale hesperiaris) considered a leading candidate based on larval appearance and habitat.
Preservation in mezcal enabled genetic analysis
The alcohol in mezcal acted as an effective preservative, maintaining the larvae’s DNA integrity despite the lack of visible distinguishing features after prolonged storage. This allowed researchers to overcome the limitations of morphological identification, which had previously prevented confirmation of the larvae’s identity despite decades of speculation.
What species is the mezcal “worm” actually?
The mezcal “worm” is the caterpillar of the agave redworm moth (Comadia redtenbacheri), as confirmed by DNA analysis of specimens from bottled mezcal.
When did the practice of adding larvae to mezcal initiate?
The practice of placing larvae in mezcal bottles began in the 1940s, much later than the centuries-old history of mezcal production itself.