Popular Science Monthly/Volume 55/June 1899/Bookworms in Fact and Fancy



"What is a bookworm? Tell me if you can;
I merely mean the insect, not the man—
A reptile whom a wit like Hood might dub
A grub that grubs in Grub Street for its grub."

Robert Rockliff.

SO much mystery has gathered around the term bookworm, so much imagery has been employed in depicting the appearance and devastations of this mythical creature, that many have been prepared to accept almost anything, no matter how fabulous, that might be said about this unknown enemy of literature. Reaction against these weird and fantastical accounts is indicated by the question, not infrequently asked, "Are there such things as bookworms?" Few are aware that in this creature we encounter another case of masquerading, that these "destroyers of the Muses" are common enough pests playing other roles than those in which they are familiarly known. Some of them are met with daily in the house and elsewhere, and arouse no unusual interest, while the world goes on wondering what a bookworm is like.

Insects injurious to books and bindings are not a new subject. The Greeks and Romans observed and wrote about them, but notwithstanding, their knowledge of zoölogy, comparatively speaking, was so meager, they do not seem to have felt any of the mystery or wonderment about these creatures which we have felt. The terms blatta, tinea, silphe, are frequently met with in the works of classical writers, and, while we can not be sure of the particular species they intended to allude to by these terms, we do in many instances know from the context that the creatures known to them had like characteristics with those known to us, and that they were given to literary depredations as are their descendants.

The earliest allusion to a book-destroying worm which has come down to us from classical lore was rescued from oblivion by the lad Salmasius in 1606, when he discovered the manuscripts of the anthology of Cephalas in the library of the Counts Palatine at Heidelberg. Among the fragments in this collection is one attributed to Evenus, the sophist-poet of Paros, who wrote about 450 B.C., in which the "foul destroyer" is thus berated:

 "O worst enemy of the Muses, devourer of the pages of books,

  Foul destroyer that lurkest in a hole, ever feeding on what thou hadst stolen from learning,

  Tell me, black-colored bookworm, why dost thou lie in ambush to injure the sacred decrees while fashioning thy envious image?"

Aristotle, in his History of Animals, mentioned the "little scorpionlike creature found in books"; a characterization which obtains to-day for the little creature which Leunis calls the "Bücherscorpion." Horace addresses his finished book, to which he imputes an unbecoming haste to be displayed on the booksellers' stalls, thus: "When thumbed by the hands of the vulgar, you begin to grow dirty, then you will in silence feed the groveling bookworm." Ovid, in his exile at Tomi, likens the "external remorse of its cares" which his heart feels to the gnawing of the tinea.

Considering the fact that Pliny is said to have comprised in his Natural History all the knowledge of the natural sciences then known, it is a little surprising that he had not more to say regarding book insects. Here and there in his writings, however, he speaks of worms in connection with books and papers in the same casual way as other classical writers, causing you to feel that he was conversant with their destructive tendencies. The epigrammatist Martial in the first century, and Lucian in the second, both use the term bookworm; Martial, in much the same way as did Horace, warning his book of the fate awaiting it; Lucian, in his well-known dialogue, The Dream; or, The Cock, as a symbol of the condition to which miserly man may descend.

Sufficient has been said to show the attitude of the ancients toward these little pests, that had no more regard for their precious thoughts than for the utterances of modern "statesmen," whose speeches are "read by title and ordered printed."

Crossing the cloistered period of the ages called dark, when books were so few and so constantly used by the jolly monks that these little creatures must have had a difficult time getting a living unobserved, we come down to the sixteenth century, by which time books had begun to multiply and worms to propagate. In the last quarter of this century we find Pierre Petit, who is numbered among the celebrated pleiade of Latin verse writers along with Rapin, Commire, and others, addressing these "impudent creatures" in a thirty-four-line Latin poem titled In Blattam.

A curious and interesting characterization of some species of book insects has come to us in the writings of Christian Mentzel, the German naturalist and philologist, who lived in the seventeenth century. When one reads that he heard the bookworm crow like a cock, and said, "I knew not whether some local fowl was clamoring or whether there was but a beating in my ears," one can not help wondering if there was not something defective in his ear drums; but further on he says, "I perceived, in the paper whereon I was writing, a little insect that ceased not to carol like very chanticleer, until taking a magnifying glass I assiduously observed him." From this one concludes that if the fault were not with his hearing, by which some well-known sounds made by book insects seemed to him like the crowing of a cock, an altogether different cock from the kind we know must have lived in his day.

The earliest observations on the subject possessing any scientific value were made by Robert Hooke in his Micrographia, published in London in 1665. In many respects this work was a curious medley of facts and fancy. The registers of the Royal Society, of which he was a member, testify to the eagerness with which Hooke hurried from one inquiry to another with "brilliant but inconclusive results." Among the many objects which engaged his attention was an insect which he described in a chapter entitled Of the Small Silver-colour'd Bookworm. His description shows it to have been the "fish-tail," by naturalists called Lepisma, well known as one of the pests that not infrequently is found in the library as well as other parts of the house.

Many interesting instances of the discovery of bookworms are found in the literature on the subject, showing the keen interest felt in the search for specimens of the "destroyer," many of them revealing the fact that some unique and curious creature which stands alone in its taste for literary food was sought. Mr. Blades reported in 1858 that he found specimens in some black-letter fragments at the Bodleian Library, that were recognized by the librarian. Dr. Bandinel, who crushed them with his thumb, saying, as he wiped his thumb nail on his coat sleeve, "O yes, they have black heads sometimes." The librarian of Hereford Cathedral, the Rev. F. S. Havergal, contributes his observations, covering a period of eighteen years, during which time he reports that he found two distinct species. From his description, however, it appears that he failed to recognize that the two were the larva and imago of the same species. Many cases of the finding of bookworms reported in England and America are not accompanied with sufficient data to determine just what they were. These contribute to the general impression that many have sought but few have found what were thought to be "genuine bookworms," while on every hand are those creatures which under the right conditions become book destroyers.

Research among the literature concerning library pests reveals the fact that no less than eleven different groups have members that are directly or indirectly accused of injuring books and bindings. The number of species in each group ranges from one to eleven, making a total of over thirty different species. In addition to these there are others against which the evidence is at best only circumstantial. It is not necessary to say that none of these bear any resemblance in any period of their existence to worms, and that the term bookworms is a misnomer. The word has become so firmly fixed in literature, both in its figurative and literal sense, that its misuse will no doubt continue.

The larger number of these are included in the class Hexapoda, or insects. Two species belong to the class Arachnida, which embraces the scorpions, spiders, mites, etc. One of these, Chelifer cancroides, known as the "book scorpion," although not a true scorpion, belongs to the order Pseudoscorpiones, and is probably what Aristotle had in mind when speaking of the "little scorpionlike insects found in books." The other species is known as Cheyletus eruditus, of the order Acarina, or "cheese mites." These two are known to be carnivorous in their habits, and there is some question as to whether they haunt books for the purpose of feeding on them or on other creatures to be found there.

Of those in the class Hexapoda, which comprises all the other known book pests, there can be no question as regards their destructiveness. Many are known about the house by the name of the article they are most frequently found in, and unless driven by a lack of those things more to their liking, they do not invade the literary sanctum. Some are so cosmopolitan in their tastes that they seem to take whatever is most convenient, whether it be books or boots, pepper or poison.

As has been said, the earliest observation of value was made by Hooke on Lepisma, commonly known as "fish moth" or "silver fish," from its resemblance, in shape and coating, to a fish; also as "bristle tail," from its caudal appendages. They are found in closets, cupboards, and clothes baskets. Opinions have differed as to its destructiveness to books, but the weight of evidence is against the insect. It seeks the paste and sizing used about books, and this leads it to attack bindings and labels. There is a theory that paste made from pure starch is not to their liking, but this is not substantiated by observation.

Termites or "white ants," another misnomer, since they are not true ants, are also well-known ravagers whose deeds of destruction assume a serious aspect, especially in the tropics. "Humboldt," according to Shimer, "informs us that in all equinoctial America, where the white ants abound, it is infinitely rare to find papers or books that go back fifty or sixty years." Their destruction to timber has been the cause of serious accidents, at one time so weakening the supports of a dwelling that a whole dinner party was precipitated from the third floor to the basement. These pests belong to the order Isoptera. The American species is known as Termes flavipes, and several well-authenticated cases of their having done serious injury to books and bindings in this country are recorded. As the chief sustenance of these insects seems to be dead wood, it may be that the increased use of wood in paper will make modern books, which bookworms are said to scorn, more tempting than ever to them.

By opening quickly some old book which has lain long unused, one may see tiny pale creatures with knowing black eyes scurrying across the pages. These insects are known as "book lice," or by the Germans as "Staublaus" (dust louse). Entomologists have given them the high-sounding name Atropos divinatoria. They belong to the family Psocidæ, of the order Corrodentia. Some writers, beginning with William Derham, in 1701, are of the opinion that this delicate little creature makes a noise like unto that of the coleopterous insect called "death-watch." These little fellows are said to have stout jaws with which they do damage to books, dried plants, etc., "nibbling away the leaves and covers of the former."

Of all the insects that injure books perhaps the best known are the cockroaches, scientifically called Blattidæ, of which there are five species whose bookish habits are unquestioned. Many instances of serious damage done by them to the bindings of books are on record, the most important, perhaps, being that of the Natural History Museum Reports, at Albany, where Mr. J. A. Lintner found a hundred volumes or more so badly damaged by roaches that they could not be moved without coming to pieces. The United States Senate Reports, bound in cloth and leather, some fresh and new, have been badly damaged at Washington, in the efforts of these pests to get at the paste with which the covers were fastened to the volumes. The species known to commit these depredations are the "Croton bug" (Blatta germanica), smaller than the others, but considered by some writers as the worst pests of the family; a little larger species, called Periplaneta orientalis; and a large species, known as Periplaneta americana, or Kakerlac. Against two other species, Blatta australasiæ and Blatta gigantea, there is not so much evidence.

Among the moths, or millers, order Lepidoptera, are found several species which injure books, the best known being the Aglossa pinguinalis, commonly called "grease moth." The larva of this species is at first a pale, flesh-colored grub, but as it matures it becomes quite black. It injures bindings by constructing long "silken tubes," in which it remains until full fed. Sometimes they spin a web between the volumes, "gnawing small portions of the paper with which to form their cocoons." This species belongs to the family Pyralididæ. Of the family Œcophoridæ two species are known to injure books: Acompsia pseudospretella, and an undetermined species of Depressaria. Under the name Œcophora, William Blades describes the ravages of the former on two leaves of a "Caxton," and accompanies his remarks with a photographic illustration of the damaged leaves, from which it is at once seen how irregular is the gnawing of this species. The newspaper account of the finding of bookworms in the Lenox Library not long ago classed the larvæ found with this species.

The largest number of book-destroying insects are found among the beetles, of the order Coleoptera. To this group belong the "book borers." The species thus far considered have been more or less dilettants in literature. The beetles, however, seem possessed with a true spirit of investigation, and when they undertake a piece of work in a serious fashion they go to the bottom of it, sticking close to the line laid down. This characteristic distinguishes these insects from all others, and makes it comparatively easy to determine when they have been at work in a worm-eaten volume. No less than sixteen different species of this order have been either detected in this work, or such strong circumstantial evidence has been found against them, that there is little doubt as to their guilt. Some insects seem to destroy books for the sheer want of something better to do; some do so in seeking the paste and sizing used in and about the books; others because the leather bindings are desirable material in which to undergo transformation; and, again, others haunt book shelves and books in search of prey in the form of living creatures. But among the beetles are found tiny little grubs that seem to have a genuine intent to destroy; that set out deliberately to wreak vengeance on man's record of his thoughts, deeds, and discoveries, and, as if knowing the means which man uses to destroy, have sought to imitate him in the effects produced. As a result we find books filled with small, round, shotlike holes strongly suggesting the results which might follow from the use of the family Bible by the restless boy as a target for his first shotgun.

The book-destroying beetles are all grouped under three families: Dermestidæ, Scolytidæ, and Ptinidæ. The Dermestidæ include the "flower beetles" and the well-known "carpet bug." The species of which there can be no doubt as to its disposition to pierce book bindings is Anthrenus varius, which Glover says "is a very pretty insect when examined under a magnifying glass, being beautifully marbled or variegated with black and gray." Another member of this family, against which there is less evidence, is Dermestes chinensis, so named by Dr. L'Herminier, of Guadeloupe, who reported a loss of nearly four hundred volumes from its ravages. Erichson believes this to have been the well-known Anobium paniceum. Dermestes lardarius and Attagenus pellio are others of this family mentioned in the same category.

The family Ptinidæ includes two groups, Anobium and Ptinus, the first being generally known as the "death-watch," from the peculiar sound, like the tick of a watch, which is produced by striking against a hard substance with their tiny jaws. Superstitious persons have long considered this noise an omen of death, hence the name. Instead of an ill omen, this noise proves itself to be a love-call between the sexes, and may be imitated accurately enough to elicit a response. One of the best known of these beetles is called Sitodrepa panicea, generally known in Europe as Anobium paniceum. It is a cosmopolitan feeder, having a reputation in several different fields of activity, commercial and scientific as well as literary. To druggists it is known as "the worm," and their stock of ginger, rhubarb, Cayenne pepper, nux vomica, and belladonna root all appear to be equally to its liking, tin foil being no formidable barrier to its persistent search. Leather dealers have suffered from the destruction wrought by this little fellow to such an extent that whole cases of boots and shoes, carriage trimmings, etc., have been ruined. To this species belongs the insect found a few years ago at work in a volume of Dante's Divine Comedy, which had been sent to Cornell University library from Florence. The larvae are about three to four millimetres in length, of a dirty-white color, head tinged with, brown, and black mouth parts, with the abdomen strongly curved. The adult is a small, cylindrical, brown beetle from two to three millimetres in length, with head bent down and wing covers marked with fine punctate striæ.

Professor Poey made extensive observations of an insect in Cuba which had destroyed about four thousand volumes. He called it Anobium bibliothecarum, and Schwartz thinks the injury reported by Herminier from Guadeloupe should be attributed to the same species. Anobium striatum and pertinax have long been known to injure books by their "gnawing and burrowing," not only in and through the bindings, but also entirely through the volumes. Nicobium hirtum, a native of southern Europe, where its larvæ have been found doing like injury, is only locally abundant, and for this reason has never been considered a serious library pest. Schwartz says, "In one way or another the insect has found its way to North America, but has always been regarded as a great rarity with us."

The Ptinus group embraces Ptinus fur, Ptinus mollis, Ptinus brunneus, and Ptilinus pectinicornis, called by Leunis "Bücherbohrer" According to Butler, a peculiarity of this genius—that of dissimilarity of shape between the sexes—is well illustrated by the P. fur, the male being almost cylindrical, the female inflated or rounded at the sides; so much variation that they might be taken for two different insects. Ptinus brunneus, although similar to P. fur, is distinguished from it by being wholly of a light-brown color and destitute of whitish bands on the wing covers. Some writers speak of this species as the "book beetle," while Sitodrepa is spoken of as the "spice beetle." Dr. Henry Shimer makes the following statement regarding their method of boring: "They usually operate in leather-bound or half-bound volumes by boring galleries along in the leather.… They usually bore along quite under the surface of the leather, cutting it almost through; occasionally a small round hole penetrates through the leather to the outer surface."

One of the most famous cases on record of insects boring through books is that reported by M. Peignot, in which he states that twenty-seven folio volumes were pierced through in so straight a line that a cord might be passed through them and all the volumes raised by means of it. Different writers give the credit of this feat to different members of this group, so that the most that can be said is that it was the work of some member of the Ptinidæ.

In the family Scolytidæ only one species belongs to the book ravagers. It is known as Hypothemus eruditus, and was described by Westwood in 1836 as "pitchy black, the head of the same color, entirely concealed from above by the front thorax." It is very minute in size, being about one twentieth of an inch in length. So far as its depredations have been observed it confines its work to the bindings of books, making furrows in all directions much as it does in the sap wood of dead trees. The strong resemblance of its burrowing to the gouging done by an engraver's chisel has given to this family the name of "engraver beetles."

A review of the different families of insects whose habits under favorable conditions lead them to infest books and bindings will show them to be more or less well defined according to their feeding habits. The book scorpions and mite, Cheyletus eruditus, which, as we have seen, do not come under the head of insects, are primarily carnivorous, and their presence in books may be due to the fact that they find there animal as well as vegetable food. This is certainly true of the book scorpion, which feeds on mites, book lice, and other small insects. The "fish moths" or "silver fish," the "book lice," and the "cockroaches" can have no other reason for infesting books than their liking for farinaceous substances such as are used in and about the bindings and labels of books. For this reason the damage done by them is largely confined to the exterior or interior of the bindings, and only so much of the book itself is injured as comes in their way in their search for food. The "white ants" feed principally on wood, and in and about books there is more or less wood fiber which would be to the liking of these voracious feeders. The moths and beetles are the burrowers and borers. They seek retired places in which to lay their eggs where the larvae will be surrounded with food for their growth. The moths and some of the beetles are more given to burrowing in the bindings, keeping close to the outer surface for the purpose, it is thought, of making it easy for the imago to emerge after the change is completed; while others bore straight tunnels often from cover to cover.

A natural conclusion for one who has gone over the literature of book-injuring pests to reach is that the many persons that have been industriously looking for the bookworm, as well as those that have reported the finding of isolated specimens, some dead, some alive, have had in mind the one creature which bored holes in books. The frequent use of the terms "genuine bookworm," "the real bookworm," etc., reveals the fact that the users of these phrases approached the subject with a preconceived idea of the kind of creature they should find to account for the ravages only too apparent on scores of volumes which pass through the hands of booksellers and book keepers. To many the boring beetles are the only creatures which are rightfully called bookworms, and in their search other book pests have not been taken into account.