120 INDIRECT INJURIES CAUSED BY INSECTS. 



than as an injury to a tree or shrub ; yet when too numerous they must 

 deprive it of its proper nutriment, and so occasion some defect. And 

 probably the enormous wens, and other monstrosities and deformities 

 observable in trees, may have been originally produced by the bite or in- 

 cision of insects. 



Besides exterior insect enemies, living trees are liable to the ravages 

 of many that are interior. These interior feeders may be divided into two 

 great classes those which bore into the heart and substance of the 

 wood, and those which feed upon the inner bark, with the adjoining 

 alburnum or sap-wood. Amongst the former the larva of a large weevil 

 (Cryptorhynchus lapathi) bores into the wood of the willow and sallow, 

 which thus in time often become so hollow as to be easily blown down. 1 

 The stag-beetle tribe, or Lucanidce, have a similar appetite ; but the most 

 extensive family of timber-borers are the Capricorn beetles 3 , including the 

 Pabrician genera of Prionus, Cerambyx, Lamia, Stenocorus, Leptura, Rha- 

 gium, Gnoma, Saperda, Callidium 3 , and Clytus. The larva of these, as 

 soon as hatched, leaves its first station between the bark and wood, and 

 begins to make its way into the solid timber (some of them plunging even 

 into the iron heart of the oak), where it eats for itself tortuous paths, at its 

 first starting, perhaps, not bigger than a pin's head, but gradually increasing 

 in dimensions as the animal increases in magnitude, till it attains in some 

 instances to a diameter of one or two inches. Only conceive what havoc 

 the grub of the vast Prionus giganteus must make in a beam ! Percival is 

 probably speaking of this beetle, when, in his account of Ceylon, he tells 

 us, " There is an insect found here which resembles an immense over- 

 grown beetle. It is called by us a carpenter, from its boring large holes in 

 timber, of a regular form, and to the depth of several feet, in which, when 

 finished, it takes up its habitation." 4 Seeing the perfect insect come out 

 of these holes, an unentomological observer would naturally conclude that 

 the beetle he saw had formed it, and lived in it ; but, doubtless, the whole 

 was the work of the grub. Of all the Coleopterous genera, there is none 

 the species of which are generally so rich, resplendent, and beautiful, as 

 those of Buprestis : these likewise, in their first state, there is abundant 

 reason to believe, derive their nutriment from the produce of the forest, 

 in which they sometimes remain for many years before they assume their 

 perfect state, and appear in their full splendour, as if nature required more 

 time than usual to decorate these lovely insects. We learn from Mr. 



1 Lewin in Linn. Trans, iii. 1. Curtis in ditto, i. 86. 



9 See Kirby in Linn. Trans, v. 250, More than a hundred species of the Capri- 

 corn tribe, many of them nondescripts, were collected near Rio de Janeiro by Captain 

 Hancock of the Foudroyant. 



5 The larva of a Callidium (which Dr. Leach has discovered to be C. bajulum) 

 sometimes does material injury to the wood-work of the roofs of houses in London, 

 piercing in every direction the fir-rafters (in which it most probably took up its resi- 

 dence while they were growing as trees), and, when arrived at the perfect state, 

 making its way out even through sheets of lead, one sixth of an inch thick, when 

 they happen to have been nailed upon the rafter in which it has assumed its final 

 metamorphosis. I am indebted to the kindness of Sir Joseph Banks for a specimen 

 of such a sheet of lead, which, though only eight inches long and four broad, is thus 

 pierced with twelve oval holes, of some of which the longest diameter is a quarter 

 of an inch ! Mr. Charles Miller first discovered lead in the stomach of the larva of 

 this insect. 



* P. 310. 



