For Akito Kawahara and his colleagues, a few shots of mezcal were well deserved after a long day of catching butterflies in Mexico’s Yucatan Peninsula four years ago. But just because booze was on the table didn’t mean the work was over.

Kawahara remembers someone mentioning that a bottle of mezcal at the bar contained one of the infamous tequila worms. When the team asked the bartender for the worm for further inspection, “he thought we were crazy,” says Kawahara, a lepidopterist (a person that studies moths and butterflies) at the University of Florida.

And yet a quick internet search revealed that the tequila worm’s species wasn’t completely clear — despite its existence being fairly common knowledge among the drinking public. “There was this mystery among the scientific community about what it actually was,” Kawahara says.

While the worm didn’t appear to be a moth larva, it was probably the larva of something; maybe a beetle or fly, the team thought initially. Purely in the interest of science, the researchers brought home some bottles of mezcal from their expedition in the peninsula and sequenced the worms’ DNA.

Tequila Worm Origins

The name “tequila worm” is actually something of a misnomer. Tequila is very similar to mezcal, but the former is made only from blue agave plants principally in and around Tequila — a town that sits between the coast at Puerta Vallarta and Guadalajara, Mexico’s second most populous city.

The famous worm is mostly found in mezcal, rather than tequila. But even with mezcal, not every bottle has a worm. “Some people think it’s just a gimmick,” Kawahara says.  

To make things more confusing, there’s also a species of butterfly called the tequila giant skipper. It possibly earned this name because the species feeds on the agave plants that produce all forms of mezcal.

In the past, due to this association, it seems that some people believed that the larvae inside mezcal bottles came from the tequila giant skipper, “but it has nothing to do with it, it’s completely wrong,” Kawahara confirms.

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Digging Deep Into the Mezcal “Tequila Worm”

The researchers sequenced the initial worms they took home, and even ordered a few more bottles available commercially in the U.S. But after deciding such a weighty scientific question required more diligent research, they organized another trip to Oaxaca — the mezcal mecca in southern Mexico.

Kawahara and his colleagues visited the state’s various distilleries in an effort “to understand the product,” he says. “It turned into a whole expedition.”

All told, they successfully sequenced 18 individual worms for a study published this year in PeerJ. The DNA revealed the species was indeed a moth: the agave redworm moth (Comadia redtenbacheri), to be exact.

These moths, which are typically between 1.5 and 2 inches in size, lay their eggs on agave plants. After hatching, the larvae burrow into the heart of the plant, where they are relatively protected from predators.

They don’t come out again until they morph into moths, or until an agave harvester unceremoniously cuts their home up for use in a mezcal distillery. And while these worms often appear pale in a bottle, they are much more colorful while alive.

“They are very red, the caterpillars — they kind of look like bright red gummy worms,” Kawahara says.

Mezcal Worms In Danger

Based on what Kawahara can tell, the worms may have ended up in mezcal as a kind of gimmick after all: Someone must have moved one of the larvae from a plant into a barrel or bottle at some point. From there, it simply caught on.

This is unfortunate, however, for the moths. Kawahara says there’s some concern that their numbers are decreasing now, due to overharvesting. “The demand is becoming higher and higher, and they are not growing the caterpillars in captivity,” he says.

Instead, mezcal distilleries pay people for them, as a form of marketing for their bottles. They’re also ground up and used in a kind of seasoning salt mixture that tastes smoky, Kawahara says.

It’s possible that the worms do end up in bottles on their own — just not in a visible way. Because the worms burrow into the plant itself, some may be crushed up in the distilling process, perhaps even imparting flavor to the mezcal.

In the course of their vigorous research, the Kawahara’s team ate several of the worms and agreed that they don’t taste very good. Still, he says, there’s plenty of other people clamoring for the chance to do follow-up research of their own.

“My students all want to go on this trip,” Kawahara says.

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