M. Peiguot mentions an instance where, in a public library that was but little frequented, _twenty-seven folio_ volumes were perforated in a straight line by one and the same larva of a small insect (_Anobium pertinax_ or _A. striatum_?) in such a manner that, on passing a cord through the perfectly round hole made by the insect, these twenty-seven volumes could be raised at once.[190] Bostrichidæ--Typographer-beetles. The Typographer-beetle, _Bostrichus typographus_, is so called on account of a fancied resemblance between the paths it erodes and letters. This insect bores into the fir, and feeds upon the soft inner bark; and in such vast numbers that 80,000 are sometimes found in a single tree. The ravages of this insect have long been known in Germany under the name of _Wurm trökniss_--decay caused by worms; and in the old liturgies of that country the animal itself is formally mentioned under its common appellation, _The Turk_. About the year 1665, this pest was particularly prevalent and caused incalculable mischief. In the beginning of the last century it again showed itself in the Hartz forests; it reappeared in 1757, redoubled its injuries in 1769, and arrived at its height in 1783, when the number of trees destroyed by it in the above-mentioned forests alone was calculated at a million and a half, and the whole number of insects at work at once one hundred and twenty thousand millions. The inhabitants were threatened with a total suspension of the working of their mines, for want of fuel. At this period these _Bostrichi_, when arrived at their perfect state, migrated in swarms like bees into Suabia and Franconia. At length a succession of cold and moist seasons, between the years 1784 and 1789, very sensibly diminished the numbers of this scourge. In 1790 it again appeared, however, and so late as 1796 there was great reason to fear for the few fir-trees that were left.[191] Cantharidæ--Blister-flies. Many species of this family of insect possess strong vesicating powers, and are employed externally in medicine to produce blisters, and internally as a powerful stimulant. Taken internally, Pliny considered them a poison, and mentions the following instance of their causing death: Cossinus, a Roman of the Equestrian order, well known for his intimate friendship with the Emperor Nero, being attacked with lichen, that prince sent to Egypt for a physician to cure him; who recommended a potion prepared from Cantharides, and the patient was killed in consequence.[192] But there is no doubt, however, Pliny adds, that applied externally they are useful, in combination with juice of Taminian grapes, and the suet of a sheep or she-goat. They are extremely efficacious, too, continues Pliny, for the cure of leprosy and lichens; and act as an emmenagogue and diuretic, for which last reason Hippocrates used to prescribe them for dropsy.[193]