Casu martzu (Sardinian)
Casgiu merzu (Corsican)
Rotten cheese
Country of origin
Region, town
Source of milkSheep
Related media on Wikimedia Commons

Casu marzu (Sardinian pronunciation: [ˈkazu ˈmaɾtsu]; literally 'rotten/putrid cheese'), 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.[1]

Derived from pecorino, casu marzu 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.[2]


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.[2][3] The eggs hatch and the larvae begin to eat through the cheese.[4] The acid from the maggots' digestive system breaks down the cheese's fats,[4] 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.[5]


Casu martzu is considered by Sardinian aficionados to be unsafe to eat when the maggots in the cheese have died.[6] 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.[6] 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.[4][7] Casu martzu is believed to be an aphrodisiac by Sardinians.[8] Because the larvae in the cheese can launch themselves for distances up to 15 centimetres (6 in) when disturbed,[2][9] 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.[10][6]

Health concerns

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.[11][12]

Because of European Union food hygiene-health regulations, the cheese has been outlawed, and offenders face heavy fines.[10] 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.[8][6]

Attempts have been made to circumvent the Italian and EU ban by having casu martzu declared a traditional food[6] (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 local Sardinian government.[13]

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.[14]

Other regional variations

Outside of Sardinia, similar milk cheeses are also produced in the French island of Corsica, as a local variation of the Sardinian cheese known as casgiu merzu, as well as in a number of Italian regions.[15][16][17]

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.[4] 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."[18]

See also


  1. ^ "Fromage corse: le Sartenais". Archived from the original on 1 May 2014. Retrieved 8 August 2014.
  2. ^ a b c Berenbaum, May R (1993). Ninety-Nine More Maggots, Mites, and Munchers. University of Illinois Press. pp. 10–14. ISBN 0-252-06322-8.
  3. ^ Stephens, Andrew (30 August 2008). "Top five ... challenging foods; eat, drink, cook ... and be merry". The Age. p. A2. Under "Casu martzu"
  4. ^ a b c d Overstreet, Robin M (December 2003). "Presidential Address: Flavor Buds and Other Delights". Journal of Parasitology. Halifax, Nova Scotia, Canada: American Society of Parasitologists. 89 (6): 1093–1107. doi:10.1645/GE-236. PMID 14740894. S2CID 34903443. Retrieved 6 October 2008. Under the "Botflies and other insects" section.
  5. ^ Hegarty, Shane (1 April 2006). "Maggots, songbirds and other acquired tastes". The Irish Times. p. 12.
  6. ^ a b c d e Mark Hay (2020). "The secret resistance behind the world's most dangerous cheese".
  7. ^ Loomis, Susan Herrmann (May 2002). "Sardinia, Italy". Bon Appétit. Archived from the original on 9 April 2006. Retrieved 8 October 2008.
  8. ^ a b Trofimov, Yaroslav (23 October 2000). "As a Cheese Turns, So Turns This Tale Of Many a Maggot --- Crawling With Worms and Illicit, Sardinia's Ripe Pecorinos Fly In the Face of Edible Reason". Wall Street Journal (Eastern Edition). 236 (37): A1. ISSN 0099-9660.
  9. ^ Bethune, Brian (16 October 2006). "The back pages". Maclean's. The agile maggots offer an additional frisson: they can bend themselves so tightly that, when they let go, the force unleashed propels them six inches or more.
  10. ^ a b Frauenfelder, Mark (2005). "Most Rotten Cheese". The World's Worst: A Guide to the Most Disgusting, Hideous, Inept, and Dangerous People, Places, and Things on Earth. Chronicle Books. pp. 22–23. ISBN 978-0-8118-4606-6.
  11. ^ Peckenscneider, L.E., Polorny, C. and Hellwig, C.A., 1952 Intestinal infestation with maggots of the cheese fly (Piophila casei). J Am Med Assoc. 1952 May 17;149 (3):262-3.
  12. ^ "Gastrointestinal Myiasis – Report of a case, Alonzo F. Brand, M.D., Arch Intern Med (Chic). 1931;47(1):149–154. doi:10.1001/archinte.1931.00140190160017". doi:10.1001/archinte.1931.00140190160017. Archived from the original on 9 January 2018. Retrieved 17 February 2018. Cite journal requires |journal= (help)
  13. ^ "Casu frazigu – Formaggi" (PDF) (in Italian). Regione autonoma della Sardegna – ERSAT: Ente Regionale di Sviluppo e Assistenza Tecnica. Archived (PDF) from the original on 22 July 2011. Retrieved 29 October 2010.
  14. ^ "Edizioni Pubblicità Italia". Archived from the original on 16 May 2013. Retrieved 1 August 2014.
  15. ^ Comuni italiani. "Cacie' punt". Archived from the original on 7 February 2011. Retrieved 30 April 2011.
  16. ^ Prodotti tipici. "Formaggio saltarello" (PDF). Archived from the original on 12 December 2011. Retrieved 30 April 2011.
  17. ^ Prodotti tipici. "Pecorino marcetto" (PDF). Archived from the original on 12 December 2011. Retrieved 30 April 2011.
  18. ^ Everyman's Library (London/New York: Dent/Dutton, 1928), Vol. II, p. 110.