INSECTS. 507 



gradually increasing, and at intervals changing their skins, 

 until they are of the size of two inches or more. At 

 this time they descend into the earth to the depth of 

 two feet, there to construct an oval cell, smooth inside; 

 and here after a certain time, they divest themselves of their 

 last skin, and appear in the chrysalis form, in which they 

 continue till the succeeding spring, when they change into 

 the perfect beetle ; for a considerable time they remain 

 in a weak state, not venturing out until the warm days 

 of May or June ; about this time the beetle emerges from 

 its retirement, and commences its depredations on the 

 leaves of plants and trees. Their antennae have a remark- 

 able comb-shaped appearance, and generally find a place 

 in the microscopist's cabinet. 



The elytra or wing-cases of diamond beetles are amongst 

 the most brilliant of opaque objects. Some are im- 

 proved by being mounted in Canada balsam, whilst 

 others are more or less injured by it : a trial of a small 

 portion, by first touching it with turpentine, decides this 

 point. 



To the genus Ptinus belongs a small beetle, known as 

 the Death-watch, fig. 262. This and the species Anobium 

 are found in our houses, doing much in- 

 jury whilst in the larva state. The eggs 

 are often deposited near some crack in a 

 piece of furniture, or on the binding of an 

 old book. As the larvae are hatched, they 

 begin to eat their way into any furniture 

 on which they may have been deposited; 

 and having attained a sufficient depth, Fig. 202. 

 they undergo transformations, and return, The Death-watch, 



i iii / i i ii T Atropvs. magnified. 



by other passages, as perfect beetles. In 

 furniture attacked by them, small round holes, about the 

 size of the head of a pin, may be seen, and to these 

 holes tbJ term worm-eaten has been applied ; and the 

 noise, made by the insect striking its head against the 

 wood, has given rise to the name of Death-watch. The 

 larva is called a Book- worm when it attacks books ; old 

 books and those seldom used, are often found bored 

 through by it. Kirby and Spence mention, that in one 

 case twenty-seven folio volumes were eaten through, in a 



