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 _Oecophoridæ_ two species are known to injure books: _Acompsia pseudospretella_, and an undetermined species of _Depressaria_. Under the name _Oecophora_, 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.