OBNOXIOUS INVERTEBRATES. 



355 



burrows out galleries, where it feeds on the juices se- 

 creted because of the irritation it occasions. These 

 burrows appear on the surface of the skin like the 

 sinuous scratches of a pin ; the larvae crawl out of them 

 and hide themselves under a neighboring epidermic 

 pellicle. 



FIG. 318. 



ITCH-INSECTS. A, male ; B, female ; pi, p 2 , p 3 , p 4 , the four pair of feet ; 6, 

 mouth ; a. anus. 



SOME INSECTS INJURIOUS TO AGRICULTURE AND TO INDUSTRY. 



Coleoptera. We have already spoken of the ravages 

 committed by beetles of various kinds and in their 

 various forms. Both the larvae and the perfect insect 

 are exceedingly destructive. There are about a hundred 

 species of beetle that live at the expense of the pine- 

 tree ; different species attack different kinds of tree, 

 some eating leaves, others preferring twigs, while some 



