There is another "Bookworm," which is often confounded with the Death-watch of the vulgar; but is smaller, and instead of beating at intervals, as does the Death-watch, continues its noise for a considerable length of time without intermission. It is usually found in old wood, decayed furniture, museums, and neglected books. The female lays her eggs, which are exceedingly small, in dry, dusty places, where they are least likely to meet with disturbance. They are generally hatched about the beginning of March, a little sooner or later, according to the weather. After leaving the eggs, the insects are so small as to be scarcely discerned without the use of a glass. They remain in this state about two months, somewhat resembling in appearance the mites in cheese, after which they undergo their change into the perfect insect. They feed on dead flies and other insects; and often, from their numbers and voracity, very much deface cabinets of natural history. They subsist on various other substances, and may often be observed carefully hunting for nutritious particles amongst the dust in which they are found, turning it over with their heads, and searching about in the manner of swine. Many live through the winter buried deep in the dust to avoid the frost. The best mode of destroying the insects which infest books and MSS. has often occupied the attention of the possessors of valuable libraries. Sir Thomas Phillips found the wood of his book-case attacked, particularly where beech had been introduced, and appeared to think that the insect was much attracted by the paste employed in binding. He recommended as preservatives against their attacks spirits of turpentine and a solution of corrosive sublimate, and also the latter substance mixed with paste. In some instances he found the produce of a single impregnated female sufficient to destroy a book. Turpentine and spirit of tar are also recommended for their destruction; but the method pursued in the collections of the British Museum is an abundant supply of camphor, with attention to keeping the rooms dry, warm, and ventilated. Mr. Macleay states it is the _acari_ only which feed on the paste employed in binding books, and the larvæ of the Coleoptera only which pierce the boards and leaves. The ravages of the Bookworm would be much more destructive had there not been a sort of guardian to the literary treasures in the shape of a spider, who, when examined through a microscope, resembles a knight in armour. This champion of the library follows the Worm into the book-case, discovers the pit he has digged, rushes on his victim, which is about his own size, and devours him. His repast finished, he rests for about a fortnight, and when his digestion is completed, he sets out to break another lance with the enemy.