People are funny about what they will eat. Animals bigger than rats are fine. Yeasts and bacteria are also fine: how else are you going to have bread and cheese? But there is a gap in the chain of life, between the big enough to count and the small enough not to bother about, where most people, at least in English-speaking countries, prefer to avoid ingesting things. Especially if they have too many legs. Given that most animal species have six or more legs, this represents a considerable restriction in gastronomic choice, and there are some who argue that we should turn to insects to feed the nine billion people expected to be alive by 2050.
Insects, as you probably are aware, have six legs and belong to the subphylum hexapoda. You might expect the next step upwards in arthropod creepy-crawliness to be called octopoda, but that term is reserved for octopuses. So spiders, ticks, and scorpions are are arachnidae. As are mites. The best-known and most well-hated mite is the dust mite, known for eating dead skin and producing allergenic excreta. Another distinguished member of the mite family is the scabies mite, responsible for the eponymous itch. So you might think that you would want to avoid mites in general, and certainly keep them out of your food if you can. Especially if they are likely to eat your food before you do. As do cheese mites.
The cheese mite, as the name suggests, is a mite that eats cheese. The most common species is Acarus siro, also known as the flour mite. Under a fairly wide range of conditions (temperature above 3°C, relative humidity above 55%) the cheese mite can be a serious pest, eating large quantities of cheese or flour and contaminating it with allergens and other pathogens. Animals fed with feed contaminated by flour mites may show reduced appetite and growth and suffer from diarrhoea. Mites will colonise cheese of any age if given a chance: old cheese is good for mites because it is more digestible, while younger cheese is good because it contains fewer fatty acids, which inhibit egg-laying. So you might think that wherever you are making or storing cheese you would want to take all necessary precautions to keep the mites away and/or kill them if they get in. Unless you are involved in some kind of cheese insurance scam.
If you think this, you might want to consider taking a mind-expanding trip to Würchwitz in the German state of Saxony-Anhalt. This small village of fewer than one thousand inhabitants has not only a museum but also an imposing monument dedicated to the cheese mite. 'Imposing' from the point of view of a cheese mite at least, since the sculpted stone mite that crowns it at a height of around two metres is at a scale of around 1 to 2000. By way of comparison, a statue of me at this scale would be by far the biggest artificial structure in the world, at well over 3.6 kilometres (2 miles) tall, not counting the ornate and tasteful plinth. The reason for this high density of acarid-related cultural offerings is that a mainstay of the local economy is the production of Milbenkäse, ('mite cheese'), a kind of cheese which would not exist without the active involvement of cheese mites, in this case Tyrolichus casei, in its production.
The raw material for Milbenkäse is low-fat quark made from cow, goat or sheep milk. Clumps of this are placed in wooden boxes containing cheese mites and rye flour, and left there for up to a year, but usually for three to six months. The rye flour is there so the mites will not eat up all the cheese. Exactly how the mites contribute to the maturing of the cheese and the forming of its flavour is not known, but it is hard to avoid the supposition that the process has something to do with their waste products. (I have come across coy references to 'digestive juices', but we all know what they are called when they get outside the digestive tract.) The result, we are informed, is a cheese that is in some way comparable to a Harzer, but rather more bitter and not really comparable to anything come and visit our village and buy it. It has a pungent after-taste and its aroma has been compared to licorice. I cannot vouch for the accuracy of this comparison, since I have never encountered this cheese in real life.
A cheese with which I personally am better acquainted is mimolette. This is a cow's milk cheese, ripened for at least six weeks but usually sold after ripening for at least a year. Its characteristic orange colour is the result of the addition of achiote colourant, and there are many other things that could be said about it which all pale into insignificance in the face of its crust. The outside of old mimolette looks like a failed attempt to model a particularly crunchy part of the surface of the Moon, and is the result of the partially successful efforts of generations of cheese mites (Acarus siro) to burrow their way into the cheese. No doubt making their own contribution to the flavour as they eat. The holes they dig allow more air into the cheese, which obviously also has an effect on the process of ripening, and one which is more often referred to when people are trying to sell it. The mites are deliberately dusted onto the cheese, which is brushed from time to time to remove the accumulated poo and mite corpses and to spread the live ones more evenly around the cheese rind.
France being what it is there is at least one other less well-known cheese which is matured in the same way. Unlike mimolette, which is industrially produced, "Le Velay" is hand made from raw milk on the farm. Nor are the mites dusted onto the cheese: the cheeses are placed on rough plank shelving in rough-walled cellars and the mites are expected to crawl onto the cheese on their own. All of this no doubt makes "Le Velay" (formerly known simply as 'fromage de pays du Velay') more authentic and more expensive.
Whichever of these cheeses you may consume, there is no avoiding the fact that you are not only eating poo-poo but also consuming mites. Some people may find this off-putting. But the sad fact is that more or less everything you eat is very likely to have a mite on it somewhere, alive or dead, even if you have just rinsed it off with boiling water. So my advice would be to forget the creepy crawlies and just enjoy the cheese. And if you allow yourself to be disgusted by a few darling little mites on your cheese, then how are you going to react appropriately to Casu Marzu? This Sardinian delicacy is produced with the assistance of 8mm long insect larvae. Which jump.
Further reading
Bad mites
Good mites
French mites
Mimolette
Le Velay
The first ever science documentary film (1903)