Part 17

There are understood to be about thirty-one species of Tinea in this country; of these many, when in the larva state, inhabit fungi or rotten wood. One beautiful species is found abundantly in granaries, its larva lives upon corn and resides in a case formed of wheat grains connected together by silken threads. Many of the species of Tineina, the great group to which the genus Tineæ belongs, are leaf-miners and form those white streaks we may often see upon bramble, honeysuckle, and strawberry leaves. The grubs of another kind may be found in Scotland, inhabiting ants’ nests, and even in a coal mine, near Glasgow, Tineæ have been found in abundance.

A very beautiful species of Tinea attacks the bark of the lime-tree until it becomes completely riddled by its destructive grubs. A fine avenue of about two hundred lime-trees forming one of the approaches to the town of Southampton was infested with this insect and the growth of the trees seriously injured by its ravages.

The furrier has cause to dread the ravages of Tinea Pellionella, which feeds on feathers and fur, and is no respecter of priceless sables and ermine. This insect makes its case with atoms of fur cut to the same length, and it works so insidiously that there is no outward sign of its evil doings until little tufts of fur begin to fall off, and then it is too late to save our valued garments. They are sure, sooner or later, to prove hopelessly destroyed.

Stuffed birds and animals can only be preserved from this annoying pest by being soaked in a strong solution of corrosive sublimate or some other poison. That this is effectual I have proved by the safe preservation of groups of stuffed birds which have hung against a wall exposed to the air without protection of any kind for the last twenty-five years; these are as fresh and bright in plumage now as when they were first obtained.

This fur-moth is perhaps the best known species in our houses; it is a small yellowish-grey insect with pale brown spots on the wings. This is, I believe, the species of which I have secured the larvæ. Fur and feathers are alike its staple diet, and it is easily distinguished from other kinds by a dark brown mark on the second segment of the grub, which mark I can discern by a magnifying glass.

The linings of chairs and sofas and the stuffing of carriage cushions, horse-hair pillows, &c., are constantly attacked by Tinea biselliella, while cloth, flannel, and any woollen material, suits the taste of the almost universal Tinea tapetzella, against whose ravages every housekeeper has to devise a variety of protective plans. The moth is so small it can creep through minute crevices—a knot-hole at the back of a drawer or a keyhole will afford it access to the winter garments which have been put away in supposed security. Tapetzella differs in appearance from the fur moth as its wings are half black and half grey, and it is also of larger size. In laying her eggs the moth has the foresight to place them rather widely apart, so that each grub may find space enough in which to feed; it is this habit which renders the creature specially destructive, as it attacks many parts of a garment and does not confine its ravages to one spot. The larva of this species forms covered galleries in which it works, mining its way along the surface of the material, and eating off the pile wherever it goes and leaving threadbare tracks behind it.

Pellionella adopts a different method. The first work of the minute grub on issuing from the egg is to form a round case in which it may live, for it does not eat unless it has a house of its own. This curious habit may be seen in many other species amongst the Tineæ. I have already mentioned one which forms its house of wheat grains; another chooses particles of stone of which it constructs its dwelling, and then feeds on the lichens which grow upon old walls. Out of the fluffy seeds of the willow one Tinea forms a sort of muff in which it lives. Other species of the group form little tents upon the leaves of the elm, oak, and many kinds of fruit-trees, these cases being so minute as to be unobserved unless the insect is moving within. One of the most remarkable of all the species is one which inhabits the leaves of the nettle. The tent looks like a tiny hedgehog, as it is formed of minute portions of the leaf glued together and studded all over with the stinging hairs of the nettle.

Mr. James Rennie in his “Insect Architecture” gives such an excellent description of the weaving operations of the Pellionella grub that I cannot do better than quote his observations upon it: “It selected a single hair for the foundation of its intended structure; this it cut very near the skin in order, we suppose, to have as long as possible, and placed it in a line with its body. It then immediately cut another, and placing it parallel to the first, bound both together with a thread of its own silk. The same process was repeated with other hairs till the little creature had made a fabric of some thickness, and this it went on to extend till it was large enough to cover its body, which (as is usual with caterpillars) it employed as a model and measure for regulating its operations. The chamber was ultimately finished by a fine and closely woven tapestry of silk. When the caterpillar increases in length it takes care to add to the length of its house by working in fresh hairs at either end; and if it be shifted to furs or feathers of different colours it may be made to construct a parti-coloured tissue like a Scotch plaid. But the grub increases in thickness as well as in length, so that its first house becoming too narrow, it must either enlarge it or build a new one. It prefers enlarging the premises, and sets to work precisely as we should do, slitting the case on the two opposite sides and then adroitly inserting between them two pieces of the requisite size. When the structure is finished, the insect deems itself secure to feed upon the fur within its reach, provided it is dry and free from grease, which the grub will not touch.”

This account shows that the moth-grub can secrete a kind of silk with which it lines its cell, but it can use other materials out of which to weave a house for itself. When that house becomes too small it knows how to put in two side-pieces to make it fit the size of its body. When full grown, this same case forms its temporary coffin, for the little creature simply closes up the entrance and hangs itself up in some convenient place until in due time it comes out a perfect moth, ready to lay its eggs and pursue the instincts of its race. Surely we must admit that these lives which are carried on in our houses are very curious and worth investigation. When we think of the minute size of these grubs (scarcely a quarter of an inch in length) and the vigour of the instinct they display, the secret mode in which they work in airless drawers and boxes, the perseverance with which the moth finds entrance into these hiding-places, we must credit this small insect with many remarkable qualities. Its lineage is extremely ancient, for it is twice mentioned in the oldest book in the Bible, and it is not a little remarkable that Job seems to have been accurately acquainted with the habits of the Tinea larvæ, since he says, in speaking of an ungodly man, “He buildeth his house as a moth, and as a booth that the keeper maketh” (Job xxvii. 18).

Both of these images point to the temporary nature of the dwelling. A booth consists of a few branches put together at the top of a pole where a man can sit and scare away wild animals from the Eastern fields of fruit and grain—an erection easily removed in a few moments; it is appropriately likened to the moth grub’s tiny case which is cast aside after a few weeks or months, when the perfect insect has emerged. There are seven or eight allusions in the Scriptures to the ravages of the moth in destroying apparel, and remembering that Eastern people are in the habit of hoarding immense stores of richly embroidered clothing as an evidence of great wealth, there can be no doubt but that the many species of Tinea which are found in Palestine were a very real danger to be guarded against with the utmost solicitude.

THE DEATH-WATCH.

“Alas! the poor gentleman will never get from hence,” said the Landlady to me, “for I heard the Death-Watch all night long.”—STERNE.

THE DEATH-WATCH.

A CURIOUS ticking sound is frequently heard in old houses full of ancient furniture, and especially during the still hours of the night. This noise, which I often hear in my own rooms, is attributed by the superstitious to some strange omen called the Death-Watch, and even in these enlightened days there are those who imagine it to presage the approaching decease of some one in the house.

But there is nothing really mysterious about it, and it will be well for us to learn all we can about this house-dweller, so that such an absurd idea may be entirely exploded.

The sound is really caused by a small beetle of nocturnal habits, the Anobium striatum. This insect is of dark brown colour and rather curious form, being so constructed that it can draw its head under the thorax out of sight, retract its six legs, and thus make itself into an oval pellet. It is seldom seen by day, unless a wall may have been newly papered; to such a wall the death-watches will often flock in considerable numbers, probably to feed upon the paste. If touched, the beetles feign to be dead, and they are so brittle as to be easily injured by handling. These insects do incredible damage by boring holes in valuable old furniture, musical instruments, panels, and skirting-boards, in fact hardly anything in the way of leather and woodwork is safe from the attack of this minute pest. The female beetle seeks a crevice in old wood, and with her ovipositor places a small white egg in it and firmly glues it in a suitable position. In twenty-one days the egg is hatched, and out of it comes a white grub much resembling that which we often find in filberts. This larva begins to bore into the wood, feeding upon it, and making those small round holes we often see to our regret in some valued piece of furniture.

The grub throws out the yellow dust of the wood—often the first indication of its being what we call “worm-eaten”—and when full grown it forms a cell in the wood in which it undergoes its change into the perfect beetle.

It is difficult to convince the ignorant that the ticking sound made by this insect is nothing more formidable than the call of the beetle to its mate! It strikes its hard-shelled head against the wood, and so gives rise to the clicking sound; other Anobiums hear it and reply in the same way, and thus the amorous duets and trios go on, often to the great annoyance of the sleepless and suffering. Do what we will, the little torments are beyond our reach, and nothing will avail to stop the noise, though on the other hand, if we wish to set it going I believe we can do so by tapping sharply upon any wainscot where the beetles are known to exist. It is strange to read how widely the fear of this insect noise has spread in other countries besides our own. Mr. John Timbs in his interesting book, “Things not Generally Known,” says: “The superstition about the Death-Watch extends from England to Cashmere, and across India diagonally to the remotest nook of Bengal, over three thousand miles distance from the entrance of the Indian Punjaub.”

The only effectual remedy for the ravages of this beetle appears to be pouring spirits of wine in which corrosive sublimate has been dissolved, into the minute holes; the spirit finds its way from one tunnel to another, and the beetles may be seen dropping out in numbers. If the piece of furniture is of large size it may require several applications to be effectual, but the process will render the wood distasteful to the insect, and probably stop its operations.

A beetle of an allied species, Anobium tessalatum, makes the same tapping sound in woodwork, and a minute insect, Atropos pulsatorius, which may frequently be found under the paper lining of picture-frames, is also credited with the power of making a clicking noise; but this can hardly be so loud as the sound of the ordinary Death-Watch beetle.

CHEESE-MITES AND FLIES.

“O would the sons of men once think their eyes And reason given them but to study flies.” POPE’S Dunciad.

CHEESE-MITES AND FLIES.

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.