FOOD OF INSECTS. 



323 



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 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 ; others both the inner bark and 

 alburnum (^Scoli/tus, &c.); others the exuding resinous or other 

 excretions ( Orthotcenia Resinella) ; a third class the pith 

 {^geria tipuliformis) ; and a fourth penetrate into the heart 

 of the solid wood (^Prionus, 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 

 TinecB); others only the lower surface of the leaf (many 

 Tortrices) ; while a fourth description devour the whole sub- 

 stance of the leaf (most Lepidopteray And of the flower- 

 feeders, while some eat the very petals {Cucullia Verhasci, 

 Xylina Linarice, &c.), others in their perfect state select the 

 pollen which swells the anthers (bees, Lepturce, and Mor- 

 dellcE) ; 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 or 

 unmanufactured state. A beam of oak, when it has supported 

 the roof of a castle five hundred years, is as much to the taste 

 of some (^Anobia) as the same tree was in its growing state 

 to that of others ; another class (^Ptini) would sooner feast on 

 the herbarium of Brunfelsius than on the greenest herbs that 

 grow ; and a third (some Tinece, Termites), to whom 



" a river and a sea 



Are a dish of tea. 



And a kingdom bread and butter," 



would prefer the geographical treasures of Saxton or Speed, 

 in spite of their ink and alum, to the freshest rind of the flax 

 plant. The larva of a little fly (^Oscinis cellaris), whose 

 economy, as I can witness from my own observations, is 



Y 2 



