FOOD OF INSECTS. 383 



sects, when told that at least thirty distinct species feed 

 upon it. But this is not all. The larger herbivorous 

 animals are confined to a foliaceous or farinaceous diet. 

 They can subsist on no other part of a plant than its 

 leaves and seeds, either in a recent or dried state, with 

 the addition sometimes of the tender twigs or bark. 

 Not so the insect race ; to different tribes of which every 

 part of a plant supplies appropriate food. Some attack 

 its roots ; others select the trunk and branches ; a third 

 class feed upon the leaves ; a fourth with yet more deli- 

 cate appetite prefer the flowers; and a fifth the fruit or 

 seeds. Even still further selection takes place. Of those 

 which feed upon the roots, stem, and branches, of vege- 

 tables, some larvae eat only the bark (Sesia apiformis, &c.), 

 others the alburnum (Semasia Wceberana), others the 

 exuding resinous or other excretions (Scoparia Resi- 

 nella\ a third class the pith (Xanthia Ochraceago], and 

 a fourth penetrate into the heart of the solid wood (Pri- 

 onus, Lamia, Cerambyx, &c). Of those which prefer the 

 leaves, some taste nothing but the sap which fills their 

 veins (Aphides in all their states), others eat only the 

 parenchyma, never touching the cuticle (subcutaneous 

 Tinete, Gracillaria ?) others only the lower surface of 

 the leaf (many Tortrices\ while a fourth description de- 

 vour the whole substance of the leaf (most Lepidopterd). 

 And of the flower- feeders, while some eat the very pe- 

 tals (Cucullia Verbasci, Xylina Linarite, &c.), others in 

 their perfect state select the pollen which swells the an- 

 thers (bees, Leptura, and Mordellte}, and a still larger 

 class of these the honey secreted in the nectaries (most 

 of the Lepidoptera, Hymenoptera, and Diptera). 



Nor are insects confined to vegetables in their recent 



