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Cheese Talk: Mites Are Right


I was in the baroque Piedmontese town of Bra, Italy, on a sunny September weekend during the Cheese 2015 festival when a rumor started flying around: One of Italy’s “illegal cheeses” was available for tasting.

The rogue wheel in question was marcetto, a sheep’s milk cheese from Abruzzo, also known as formaggio con i vermi or “cheese with worms.” It’s closely related to the Piedmontese bross ch’a marcia (“the cheese that walks”) and the more well-known Sardinian delicacy casu marzu (“rotten cheese”)—for extreme foodies, sampling these rarities is the equivalent of free diving with a great white.

The hint with all of these cheeses is in the name. Producers intentionally leave the freshly made pecorino out so that the cheese fly (Piophila casei) can lay eggs in the paste. While the cheese matures, the tiny, nearly translucent fly larvae (called salterini, or “little jumpers,” as they’re capable of leaping up to six inches) vigorously emerge and begin to chew—and excrete—their way through the cheese.

After two to three months, the top of the cheese is removed with a knife and the soft—liquidy in some spots—larvae-ridden interior is exposed. It’s a stinker, heavily ammoniated, and its taste follows suit, reminiscent of an aged Gorgonzola. While rich blue cheese fans may be the only ones enticed by the flavor, it’s the gooey consistency—the result of the larvae’s digestive acid interacting with the cheese—that is apparently most memorable.

That said, slurping down the live maggots along with the cheese is probably fairly memorable, too. As the maggots are difficult to extricate—a cheese fly can lay up to five hundred eggs at a time—these cheeses are sometimes sealed in airtight bags, ultimately asphyxiating the larvae so they can be removed before consumption. Your doctor would advise the latter, as the swallowed larvae can survive in the digestive tract and potentially cause enteric myiasis, an internal infestation that we don’t recommend searching in Google Images.

It’s not only the Italians who enjoy pests with their cheese—nearby Corsica has a casu marzu equivalent in casgiu merzu. And there are tiny insect collaborators beyond the cheese fly; French mimolette is (in)famous for its mild flavor, for being French president Charles de Gaulle’s favorite cheese, and for being banned in the United States by the FDA in 2013. What the administration took exception to was how mites (Tyrophagus casei) are encouraged to burrow into this Edam style’s rind, which creates the cheese’s trademark rugged exterior. So why do it? By embracing the critters—rather than eradicating them, as their cheesemaking brethren are wont to do—this group of artisans is keeping tradition alive and producing a richer-tasting cheese in the process.

Mites also play a role in the production of the German quark-based Milbenkäse. The technique, dating back to the Middle Ages, involves mixing the salted quark with caraway seeds, then shaping and interring it in a wooden box containing rye flour and cheese mites. The bugs graze on the quark’s developing rind; the rye flour sustains them just enough so they refrain from demolishing the entire cheese. The arthropods’ digestive juices infuse the paste, influencing the taste and promoting fermentation. The color of the rind, which changes from yellow to rust and, after a year, to black—due to an interaction between fermentation and the mites’ fluids—helps determine the ripeness of your Milbenkäse.

But Milbenkäse, like casu marzu, is not beloved by EU hygiene regulators, and both currently fall into a legal gray area in Europe—that is, production is tolerated, but sales are frowned upon (not that there’s a huge demand among deli goers for wriggly pests in their purchases). But if you think about it from a fundamentals-of-cheesemaking perspective, the bugs are just another tool in the arsenal of producers who introduce outside agents—be it starter culture microorganisms or Penicillium roqueforti artfully veining creamy Stilton—to influence maturing curd.

As for the marcetto, I was delighted to encounter a small, hollowed-out round at Cheese 2015’s stand B55. The kind attendant scraped some crumbs onto a piece of bread and handed it over. The initial mellow, nutty sheep’s flavor gave way to a bitterness that settled in my molars for about an hour. Sad to report that all the larvae had been gobbled by other samplers—or leapt to freedom—ahead of my arrival.

The early bird and all that…

Feature Photo Credit: JPC-PROD | Shutterstock

Chris Allsop

Chris Allsop is a UK-based food and travel writer whose work has appeared in The Guardian, The Sunday Times Travel Magazine, and Yahoo!, among other titles. He lives in Bath, where he eats way too much cheddar.