If you come across a piece of Mimolette at a French cheese shop, you might look at it with a magnifying glass. You'll likely see a bunch of crumbs moving constantly, tiny specks that sometimes jump. These are cheese mites.
The Definition of Cheese Mites
Cheese mites are microorganisms that exist everywhere, but they especially love the damp, cool atmosphere found in the cave d’affinage, or cheese-aging chamber. They flock to cooked, pressed cheeses like Comté or Cantal, boring into the crust, moving steadily towards the softer center, leaving behind a floral, sweet flavor. If left to their own devices, cheese mites will take over a piece of cheese until it becomes inedible. Many hard kinds of cheese are treated to deter cheese mites. For example, the rind of Parmesan is oiled and cheddar is traditionally wrapped in cloth.
A Brownish Dust
Cheese mites are so tiny that the naked eye can't usually detect them. Their presence is detected by very fine brownish dust on a wheel of cheese. A joke among cheesemongers is that if you brush the "dust" off the rind of a wheel of cheese and a few hours later the "dust" has moved to a new location, you know the cheese has been infested by mites.
This "dust" is really an accumulation of living mites, dead mites, mite excretion, and cheese debris. It sounds unappetizing but is really quite harmless, unless you have a severe allergy to mites. Mites are present in all different types of dry goods, like grains and flours, without causing direct harm to humans.
Mites tend to be present on the outside of hard cheeses, such as Cheddar and Mimolette. Usually, the mites can be brushed off the rind of the cheese without affecting the flavor of the cheese inside. Some people even think that mites give cheese more flavor, which is the case with Mimolette.
Mimolette and Mites
There is one French cheese that welcomes these microscopic creatures and uses them as part of its aging process: Mimolette. Produced in Lille, near the Dutch-Belgian border, it’s a hard, orange cheese (similar to Edam) with a thick crust riddled with holes. Mimolette starts out like any old pressed cheese, but at one or two months old, it’s taken to a special chamber and inoculated with artisons. They nibble relentlessly, burrowing into the crust, aerating the cheese, and dramatically reducing the Mimolette's bulk. The result is a dense, salty cheese, with earthy, sweet, almost caramel, undertones. Alas, for American cheese lovers, aged Mimolette was banned by the FDA, who declared the excess of mites an allergen and health hazard.
One of the key factors in limiting mite damage is early intervention, such as brushing or vacuuming (both must be done regularly to have significant effect) the outside of the cheese. Once the mites work their way under the surface of the cheese they gain a measure of protection from any attempts to disrupt them.
For an interesting story about cheese mites, listen to this podcast of the radio show "Good Food" called "Cheese Mites: Pests or Flavor Enhancers?"