138 



THE LONGICORNIA. 



all events of the large species, remain in that vora- 

 cious condition for several years ; they undergo their 

 further metamorphosis in the interior of the galleries 

 which they have excavated, and eat their way out on 

 arriving at the perfect state. In this way they often 

 make their appearance in timber yards, the larvae or 

 pupae having been enclosed in the timber before it was 

 cut down, and the same circumstance explains the 

 frequent occurrence of living exotic species in this 

 country. Some idea of the power of the jaws of these 

 insects may be formed from the fact, that both the 

 larva and imago of one of our common species (the 

 Callidium bajulus) have been known to gnaw through 

 lead ; and in one instance, recorded by Mr. White, a 

 specimen of this insect, whose larval residence had 

 been worked up into the coating of a water-pipe, 

 actually ate through the lead pipe in his attempts to 

 make his way out, and was drowned by the sudden 

 rush of water, caused by his misdirected efforts. 



For the deposition of their eggs, the females are 

 provided with a long, tubular, jointed ovipositor, by 

 which the eggs are placed beneath the bark of trees. 

 It seems probable, however, from the structure of 

 this organ, that an aperture must first be formed by 

 the mandibles, and this is known to be the case in 

 some instances. Most of the species have the power 

 of producing a curious creaking noise, by the friction 

 of the hinder margin of the prothorax over the base 

 of the scutellum, which is covered with fine transverse 

 lines like those of a file. During the emission of the 

 sound, the prothorax with the head is alternately 

 raised and depressed, so as to rub the inner surface 

 of the back of the prothorax over the surface thus 

 prepared, 



