328 TRANSFORMATIONS OF INSECTS. 



insect was the author of the destruction of the trees, for when 

 a branch was carefully opened it was found to contain the living 

 larvae and nymphs of the Oncideres. 



In the engraving on page 327 a beetle may be noticed with very 

 long horns upon a little twig close to the main branch. Quite 

 low down the fractured end of the branch shows in the centre 

 the ragged pith, but between this and the bark the tissues are 

 perfectly smooth, the bark being cut through in a circular manner. 

 The smoothness of the tissues has been produced by the gnawing 

 of the beetle, which does not touch the pith. Within the branch, 

 and on a level with the beetle, there is a larva which has made 

 an excavation. A larva is also represented on the left hand side 

 of the plate. Below, a nymph may be seen in a cavity, and there 

 is one represented outside the branch on the right-hand side. 

 Now, what is the reason that the beetle should cut away the 

 branch } If it is that which is usually considered to be true by 

 naturalists, it is a most wonderful instance of superior instinct. 

 It is supposed that the branch is cut off in order to prevent an 

 unusual supply of sap flowing into it, or with a view of diminish- 

 ing the amount of sap circulating generally in the branch. Were 

 the incision not made through the bark and the flow of the sap 

 not checked, the larvee would suffer from too great abundance of 

 liquid in their immediate neighbourhood ; and the diminution of 

 the sap is necessary for the perfection of the metamorphoses. 



The ChrysomelidcB are leaf-eating insects, and attack all kinds 

 of plants. Many of them are ornamented with most beautiful 

 colours of gold, red, copper, bronze, metallic green, deep blue, 

 azure violet, and silver, and very few of them are of a sombre 

 hue. Unlike those just described, the larvae of these beetles 

 generally live in the open air, fixed upon the leaves of plants 

 or trees. They are stout, thick-set, and having very small legs, 

 they walk but very slowly, and many of them, on account of their 

 having soft integuments, protect themselves from danger in most 

 interesting and curious manners. The beetles of the genus Crio- 

 ceris are oblong creatures, with very narrow heads and fore-parts 

 of the body, and they may be constantly seen upon the twigs 

 and leaves of the beautiful white lilies which are grown in gardens. 

 They may be recognised by their brilliant black colour, which is 



