IT is not an altogether pleasant idea to dwell upon, that the very food we eat is sometimes tenanted by various forms of life. We can guard against meal-worms in the flour-barrel, and keep weevils from devouring our peas and beans; flies can be kept from the larder, and our dainties may be protected from the marauding cockroach; but by general consent we allow our cheese to be the home of a species of fungus, innumerable mites, and the grubs of a minute fly. Not only so, but most people prefer a Stilton or Cheddar cheese in a mitey condition, as it then possesses a heightened flavour. The first glimpse through a good microscope of a mass of cheese-mites is somewhat startling. We see a confused heap of struggling insects, and the idea of eating them at our next repast is by no means agreeable. Still they are worth examination as a type of a large class of animalcules which have for their object the destruction of many substances which might taint the air and do harm if they were allowed to remain in a state of decay.

The Cheese-mite has an almost transparent oval body tapering to a snout-like head. It can move with some agility upon its eight brownish-coloured legs. In sunlight this creature’s globular polished body shines as though it were made of crystal. This mite lays eggs abundantly, and also produces young alive, so this double mode of production may account for the rapid increase of the colonies in an ancient cheese.

The generic term Acarus includes a large number of species. There are those which, to the dismay of the entomologist, are found destroying his finest butterflies and moths, and reducing his cherished specimens to a little heap of dust. Some special kinds of mites prey upon figs, prunes, honeycomb, sugar, and sweetmeats of various kinds. A special mite is found in the cavities of the bones of skeletons; indeed, there seems scarcely any limit to this widely-spread family of minute depredators.

Other branches of the family are represented by the Red Spider, which is one of the plagues of our greenhouses, for, although so small as to be scarcely discernible by the naked eye, it sucks the juices of plants and often effectually prevents the healthy growth of valuable specimens.

The Plum-mite may frequently be seen in clusters upon fruit-trees, puncturing the bark and doing considerable injury to the smaller twigs.

A closely allied species is known as the Harvest-bug. This almost invisible atom burrows into the human skin and there deposits its eggs, causing excessive irritation and annoyance to the workers in corn-fields.

I will now turn from the mites to another cheese-inhabitant, Piophila casei. Few people are likely to have noticed the perfect insect, a small black fly with whitish wings margined with black; it is very inconspicuous, and we should hardly suspect its object in visiting our cheese. When cheeses are made and placed in a room to dry, before the outside rind has had time to harden, the Piophila will seek out some crevice in which to deposit its eggs. The creature is furnished with an ovipositor, which it can thrust out to a great length so as to penetrate to a considerable depth into the cracks of the cheese, and there it will lay as many as two hundred and fifty eggs. These hatch into white grubs without feet, but having two horny claw-shaped mandibles which enable them to bore into the cheese upon which they feed.

The breathing apparatus of the cheese-maggot is very remarkable, consisting of two tubes at the head and two at the tail, so the grub can breathe at either end of its body. Lest any particles of cheese should obstruct the front pair of tubes the little creature has the power of drawing over them a fold of the skin, and whilst they are thus closed it breathes through the air-tubes in the tail. A cheese inhabited by these grubs soon grows moist and rotten, because they have the power of emitting a liquid which softens and corrupts the cheese and renders it suitable for the food of the maggot.

The leaping power of these larvÆ is truly surprising. Swammerdam, who seems to have carefully studied this creature, says: “I have seen one whose length did not exceed a fourth of an inch leap out of a box six inches deep, that is twenty-four times the length of its own body.” The grub cannot crawl, as it has no legs; it must therefore progress by leaps; this it achieves by erecting itself on its tail, which is furnished with several knobs or warts to enable it to keep its balance; then, bending itself into a ring, it lays hold of the skin of its tail, and, suddenly letting go with a jerk, it can, by a succession of springs, cover a surprising distance on a level surface. In considering the life-history of this despised creature I cannot but endorse the devout remark of the great naturalist I have just quoted. He says: “I can take upon me to affirm that the parts of this maggot are contrived with so much art and design that is impossible not to acknowledge them to be the work of infinite power and wisdom from which nothing is hid and to which nothing is impossible. It could not be the production of chance or rottenness, but the work of the same Omnipotent Hand which created the heavens and the earth.”