Contrary to popular belief, the worm is not found in tequila. The worm is actually a larva of a moth that lives on the agave plant, which is used to produce mezcal. Mezcal is a spirit that is similar to tequila but is made from a different type of agave plant and has a smokier flavor. The worm is added to some bottles of mezcal as a marketing strategy and is not present in all bottles. The worm is called "Gusano de Maguey" and is a typical insect from Oaxaca, the motherland of mezcal. It grows in the roots of the agave plant and is eaten as a delicacy in some parts of Mexico. The worm does not add anything to the flavor of the drink, and there are no proven side effects that come with consuming it. The Mexican Standards authority actually prohibits adding insects or larvae to tequila, so you will never find a worm in a bottle of tequila.