FOOD OF INSECTS. 383 



thirty distinct species feed upon it. But this is not all. 

 The larger herbivorous animals are confined to a fo- 

 liaceous 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 sup- 

 plies appropriate food. Some attack its roots ; others 

 select the trunk and branches ; a third class feed upon 

 the leaves ; a fourth with yet more delicate 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 vegetables, some 

 larvae eat only the bark (Sphinx apiformis^ &c.), others 

 the alburnum (Tortrix Wcebermia), others the exuding- 

 resinous or other excretions (Tinea Resinella), a third 

 class the pith (Noctua Ochraceago^ Lep. Brit.), and a 

 fourth penetrate into the heart of the solid wood (Ce- 

 ramhyces). 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 Tinece), others only 

 the lower surface of the leaf (many Tortices), while a 

 fourth description devour the whole substance of the 

 leaf (most Lepidoptera). And of the flower-feeders, 

 while some eat the very petals (Noctua Verhasciy Lina- 

 ricBy &c.), others in their perfect state select the pollen 

 which swells the anthers (bees, Lepturce^ and Mordel' 

 Ice), and a still larger class of these the honey secreted 

 in the nectaries (most of the Lepidoptera^ HymenO' 

 ptera, and Dipt era). 



Nor are insects confined to vegetables in their re- 



