Fig. 62.—a, the death-watch beetle (Xestobium tessellatum) of the natural size (one-third of an inch long); b, the same beetle enlarged; c, the beetle (Anobium domesticum) whose grub is the furniture-worm, of the natural size, a side view.
A closely-allied and somewhat smaller species of Anobium common in houses is of a more voracious character, not confining itself to dry wood, but eating bread, biscuits, rhubarb, ginger, and even cayenne pepper. This second kind, called Anobium paniceum, is the real “book-worm”; it gets into old libraries, and the grubs bore their cylindrical tunnels from cover to cover of the undisturbed volumes. In a public library twenty-seven folio volumes standing side by side were perforated in a straight line by one individual Anobium grub or book-worm, and so regular was the tunnel thus eaten out that a string could be passed through the whole length of it, and the entire set of twenty-seven volumes lifted up at once by it.
There are one or two other grubs which less commonly injure books, and pass as “book-worms.” But the most notable of the insect enemies of books and papers is a curious little wingless insect which never passes through a grub stage of existence, but hatches out in the complete form of his parents. He is about a third of an inch long, has the shape of an elongated kite, with a long tail and six legs, and is called by old writers “the silver-fish,” and by entomologists Lepisma ([Fig. 63]). This little pest does not burrow, but nibbles, and has destroyed many a valuable old document and ancient book. Paste and sugar are a great attraction to him, and he will destroy a boxful of printed labels or a valuable manuscript, leaving only the ink-marked parts untouched, but ready to crumble.
Closely allied to the book-worm beetle, Anobium, is a larger beetle, called Xestobium tessellatum ([Fig. 62] a) which infests old woodwork, its grubs making correspondingly larger tunnels. The entire woodwork of a house has had to be removed and replaced in consequence of this creature’s depredation, and such pieces of furniture as a four-post bedstead have been riddled and made rotten in two or three years by its burrowing. It is still common in England in old wood-panelled rooms and in wooden mantelpieces. The most interesting fact about it is that it is the maker of those nocturnal tappings which are known as the “death-watch.” It is the beetle itself ([Fig. 62] a), not the grub, which makes these sounds. It makes them by deliberately striking the wood on which it stands, with its head. The taps are usually from five to seven in quick succession, the sound dying away in intensity in the later strokes. A second, and even a third, beetle will then reply with similar taps from the woodwork of some other part of the room. Years ago I used to be gently lulled to sleep by these “raps” in my rooms at Oxford, accompanied by the sound of spasmodic rushes of mice behind the woodwork. At first I thought the tapping was caused by the falling of drops of water through a leaky roof, but soon ascertained the actual cause. One does not notice these tappings until the dead of night when all else is still, and they are so mysterious and persistent that one can understand superstition arising in connection with them, and that the nerves of any one already overwrought, might be so affected by them as to lead to the belief that evil spirits are “rapping,” or that a ghostly coffin is being nailed together for a dying man. The little beetle has often been tracked by a naturalist, and discovered in some concealed position nodding its diminutive but hard head with sharp jerks, and producing an almost incredible volume of sound in proportion to its size. If the beetle, when discovered, is kept in captivity in a wooden box, it is easy to set it “tapping” or “rapping” by tapping oneself with a pencil on the table on which the box is placed, when the faithful little death-watch will unfailingly reply. Possibly some of the “raps” recorded by the pioneers of spirit-rapping, when not produced by the toes of designing mediums like the young ladies of Rochester, N.Y., were actually made by death-watch beetles. It is certain that the somewhat eccentric supposition that disembodied spirits endeavour to make signals to living humanity by “rapping” owes its origin (long before the nineteenth-century craze for “spirit-rapping”) to the measured tap-tap-tapping of the death-watch beetle, and the consequent superstition at a time when the beetle was not known to be the “tapper.”
Whilst the bigger beetle, Xestobium, is the common death-watch, it has been proved that the little furniture beetle, Anobium, is also a tapper, making regular and persistent strokes like the ticking of a watch. Another insect, called the book-louse (Atropos divinatoria), very minute, only one-twentieth of an inch, soft, white, and wingless, not a beetle at all, but also a devourer of literature ([Fig. 64]), is declared by some good observers to be a “ticker” or “tapper,” but other naturalists deny that it can make such sounds. It seems unlikely on account of the extremely small size and softness of the book-louse, but the matter needs further investigation.
Fig. 63.—The silver-fish insect (Lepisma saccharina). The line to the right shows its natural size.