Contrary to popular belief, the 'worm' found in some bottles of Mezcal is not a traditional Mexican requirement, nor is it actually a worm. It is the larva of a moth called *Comadia redtenbacheri* that lives on the agave plant. The practice of adding the larva (called a *gusano*) began in the 1940s as a marketing gimmick to differentiate certain brands and to prove the alcohol's potency (it was believed that if the larva stayed intact, the alcohol was high quality). High-end artisanal Mezcals almost never include the larva. Mezcal itself is distinguished from Tequila by its smoky flavor, which comes from roasting the agave hearts (piñas) in underground pits lined with hot rocks, rather than steaming them in ovens.