544 PHYSIOLOGY. 



merable, that even a superficial account of our native plants, and the 

 insects that dwell upon them, would fill a volume : we will therefore 

 limit ourselves to the enumeration of the chief families that consume 

 leaves, and cite from them the most interesting genera. Among the 

 beetles we find the large family of the Chrysomela, both as larva and 

 imago, select leaves for their food, and they are therefore usually found 

 upon plants. Thus we find Gallcruca tanaceti upon the Tanacetum 

 vulgare ; G. viburni upon Viburnum opulus ; G. nymphea upon 

 water plants Nymphea, Alisma, Sagittaria ; G. Alni upon Alnus 

 glutinosa ; Chrysomela pallida upon Sorbus aucuparia ; C/ir. varians 

 and Chr. centaurei, F. } upon Hypericum perforatum; Chr. Sophite upon 

 Sisymbrium Sophia L. ; Chr. vitellince upon Salix vitellina ; Lema 

 Asparagi and L. 12-punctata upon Asparagus officinalis Lema 

 merdigera and L. brunnea upon Lilium martagon, &c. All these 

 beetles and their larvae have the peculiarity of not in general consum- 

 ing the leaf from its margin, like the caterpillars of the Lepidoptcra, 

 but they bite a hole into the substance, around which they continue to 

 eat. Thus both these destroyers may be distinguished from each other 

 by the appearance merely of the leaf that has been attacked. Other 

 families of beetles do not restrict themselves so exclusively to leaves, 

 yet many, for example, the Malacoderma, Melolonthodea, Vesicifica, 

 the Cassidce (particularly the larvae) and other genera devour leaves by 

 preference. 



Of the remaining orders it is, especially in that of the Hymenopiera 

 and among the family of saw-flies (Te?ithredonodea), that we find leaf- 

 devouring insects. The pseudo caterpillars of these insects, deposited 

 even by the mother as an egg in the parenchyma of the leaf, devour the 

 leaves with incredible voracity, and thereby frequently destroy entire 

 plantations. Thus the large larva of Cimbex vuriabilis lives chiefly 

 upon willows, of C. lucorum upon the birch, of Hylotoma roses upon 

 roses, of the different species of Luphyrus upon different pines and 

 firs, L. pint, for instance, upon Pinus silvestris, of L. laricis upon 

 Firms larix, &c. The true saw-flies (Te/ithredo) are the most numerous 

 of all, and destroy cherries (Prunus cerasus), alders (Alnus glutinosa}, 

 willows (S. alba, <S. caprcea, and many others), roses (Rosa canina), 

 and many other plants. Where they are numerous upon a tree they 

 speedily destroy all the leaves, and the tree, already sjckly from the loss 

 of its organs of respiration, dies. Thus, one known by the name of 

 the slug-worm, living upon the plum, some few years ago destroyed 



