Known as “rotten cheese”, Sardinia’s casu marzu is made from Pecorino that has gone bad – really bad. The larvae of cheese flies (piophila casei) are added to the Pecorino, hatching inside, burrowing around and digesting the fats. The result is a weeping, tongue-burning delicacy that you can eat with or without the maggots.
Casu marzu is a controversial Italian sheep’s milk cheese originating from Sardinia. The cheese is derived from the Pecorino family of cheeses and has a soft-ripened texture with a natural rind.
In English, casu marzu means rotten cheese, referring to live insect larvae (maggots) which can be found in it. After the fermentation process, larvae are introduced to the cheese, promoting decomposition and breaking down the cheese’s fats.
As a result, the texture of this notorious cheese becomes very soft. Casu marzu is typically cut into thin strips and spread on pane carasau, and it is recommended to pair it with a glass of strong red wine, but only if you find the cheese on the black market as it is illegal in the EU.
Just make sure to cover your eyes while eating casu marzu, because the maggots can leap up to 6 inches off the cheese.
Casu martzu (Sardinian pronunciation: [ˈkazu ˈmaɾtsu]; literally ‘rotten/putrid cheese’), sometimes spelled casu marzu, and also called casu modde, casu cundídu and casu fràzigu in Sardinian, is a traditional Sardinian sheep milk cheese that contains live insect larvae (maggots). A variation of the cheese, casgiu merzu, is also produced in some Southern Corsican villages like Sartene.
Derived from pecorino, casu martzu goes beyond typical fermentation to a stage of decomposition, brought about by the digestive action of the larvae of the cheese fly of the Piophilidae family. These larvae are deliberately introduced to the cheese, promoting an advanced level of fermentation and breaking down of the cheese’s fats. The texture of the cheese becomes very soft, with some liquid (called làgrima, Sardinian for “teardrop”) seeping out. The larvae themselves appear as translucent white worms, roughly 8 mm (0.3 in) long.
Casu martzu is created by leaving whole pecorino cheeses outside with part of the rind removed to allow the eggs of the cheese fly Piophila casei to be laid in the cheese. A female P. casei can lay more than 500 eggs at one time. The eggs hatch and the larvae begin to eat through the cheese. The acid from the maggots’ digestive system breaks down the cheese’s fats, making the texture of the cheese very soft; by the time it is ready for consumption, a typical Casu Martzu will contain thousands of these maggots.
Casu martzu is considered by Sardinian aficionados to be unsafe to eat when the maggots in the cheese have died. Because of this, only cheese in which the maggots are still alive is usually eaten, although allowances are made for cheese that has been refrigerated, which results in the maggots being killed. When the cheese has fermented enough, it is often cut into thin strips and spread on moistened Sardinian flatbread (pane carasau), to be served with a strong red wine like cannonau. Casu martzu is believed to be an aphrodisiac by Sardinians.
Because the larvae in the cheese can launch themselves for distances up to 15 centimetres (6 in) when disturbed, diners hold their hands above the sandwich to prevent the maggots from leaping. Some who eat the cheese prefer not to ingest the maggots. Those who do not wish to eat them place the cheese in a sealed paper bag. The maggots, starved for oxygen, writhe and jump in the bag, creating a “pitter-patter” sound. When the sounds subside, the maggots are dead and the cheese can be eaten.
According to some food scientists, it is possible for the larvae to survive the stomach acid and remain in the intestine, leading to a condition called pseudomyiasis. There have been documented cases of pseudomyiasis with P. casei.
Because of European Union food hygiene-health regulations, the cheese has been outlawed, and offenders face heavy fines. However, some Sardinians organized themselves in order to make casu martzu available on the black market, where it may be sold for double the price of an ordinary block of pecorino cheese. As of 2019, the illegal production of this cheese was around 1,000 quintals per year, accounting for 2 to 3 million euros.
Attempts have been made to circumvent the Italian and EU ban by having casu martzu declared a traditional food (it has been made in the same manner for more than 25 years, and it is therefore exempt from ordinary food hygiene regulations). The traditional way of making the cheese is explained by an official paper of the Sardinian government.
A cooperation between sheep farmers and researchers of the University of Sassari developed a hygienic method of production, in 2005, aiming to allow the legal selling of the cheese.
Outside of Sardinia, similar milk cheeses are also produced in the French island of Corsica, as a local variation of the Sardinian cheese produced in some Southern villages and known as casgiu merzu or casgiu sartinesu, as well as in a number of Italian regions.
Several other regional varieties of cheese with fly larvae are produced in the rest of Europe. For example, goat-milk cheese is left to the open air until P. casei eggs are naturally laid in the cheese. Then it is aged in white wine, with grapes and honey, preventing the larvae from emerging, giving the cheese a strong flavour. In addition, other regions in Europe have traditional cheeses that rely on live arthropods for ageing and flavouring, such as the German Milbenkäse and French Mimolette, both of which rely on cheese mites.
An early printed reference to Stilton cheese points to a similar production technique. Daniel Defoe in his 1724 work A tour thro’ the whole island of Great Britain notes, “We pass’d Stilton, a town famous for cheese, which is call’d our English Parmesan, and is brought to table with the mites or maggots round it, so thick, that they bring a spoon with them for you to eat the mites with, as you do the cheese.”
