It is a common misconception that some tequilas contain a 'worm' in the bottle. Only certain mezcals, usually from the state of Oaxaca, are ever sold con gusano (with worm), and that only began as a marketing gimmick in the 1940s. The worm is actually the larval form of the moth Hypopta agavis, which lives on the agave plant. Finding one in the plant during processing indicates an infestation and, correspondingly, a lower-quality product. However, this misconception continues, despite effort and marketing to represent tequila as a premium liquor—similar to the way Cognac is viewed in relation to other brandies.