COLEOPTERA. 



723 



The mandibles are well developed ; the first maxillae have 

 each two well-marked lobss and a palp ; the second maxillae are 

 somewhat reduced, with a well-formed palp, and are very com- 

 pletely fused to form a labium. The legs are usually well 

 developed, and the tarsi may have from one to five segments, 

 a detail of great systematic import. The metamorphosis is 

 complete. The larvae are as a rule grub-like, but they vary 

 greatly, from well-marked campodeiform active creatures to 

 legless grubs. As a rule a head, three thoracic segments with or 

 without legs, and nine abdominal segments are patent, but in 

 many cases the abdomen presents ten segments. When exposed 

 the larvae may have a hard and coloured integument, but 

 those which lead a hidden life are usually white and soft. 



The pupa usually is hidden in the earth or concealed near the 

 larval food. It is, as a rule, an unpleasant, whitish-looking, soft 

 object with all its appendages projecting, but some families have 

 obtected pupae whose 

 limbs are fused to the 

 body. In many, a cocoon 

 of some extraneous 

 material, is formed, and 

 as a rule the period 

 passed in the pupal sta- 

 dium is short and does 

 not surpass a very few 

 weeks. 



There is a long oeso- 

 phagus, and in the carni- 

 vorous beetles a well- 

 developed muscular 

 proventriculus. As a 

 rule the number of mal- 

 pighian tubules is four 

 or six. The central nervous system varies in its degree of 

 concentration. The ovarian tubules are many on each side, 

 with very numerous ova ; the male possesses a penis which is 

 usually retracted into the abdomen. 



Anobium, the so-called " death-watch," produces its sounds 

 by a tapping movement. Longicorn beetles make a sharp 

 sound by rubbing the scutellum against the edge of the pro- 



FIG. 460. Hydrophilus piceus. a beetle ; !> larva 

 c pupa. 



