INSECTS. 253 



potato-beetle (fig. 67), and others which feed upon the 

 grape, the asparagus, etc.; and near them are the so-called 

 weevils (fig. 75) which attack peas and beans. 



The oil-bottles and blister-beetles are a curious group, 

 since in their young stages 

 many of them are parasitic 

 upon other insects, while 

 when adults they contain a 

 peculiar substance which 

 will raise a blister upon 

 human flesh. Hence some 

 of these are killed, dried, 



fmrl form x rpo'iilnr nrtiolp nF FlG - 75. Pea-weevil (Bruchus pisi}, 

 lOrm a regular ar natural size and enlarged. b, pea 



commerce under the name 



of Spanish flies and are used in the manufacture of blis- 

 tering-plasters. 



ORDER VI. HYMENOPTERA (Bees, Wasps, Ants). 



Bees, wasps, and ants are the better known represen- 

 tatives of this group, all the members of which agree in 

 having four membranous wings (the front pair the larger) 

 with comparatively few cross-veins. The mouth-parts are 

 fitted both for biting and for sucking. There is a com- 

 plete metamorphosis. So far as we can judge, these are the 

 most intelligent of all insects, and the student who investi- 

 gates their habits is continually rewarded by new facts, 

 which show that their small brains are most highly devel- 

 oped. In other points of structure, however, they are 

 much less complicated. 



In the lower forms the female is provided with an ovi- 

 positor, frequently of great length, which is well adapted 

 for boring. In the higher this ovipositor is modified into 



