WOOD-BOEING INSECTS. 203 



The mode in which the Sirex carries on its operations is 

 simple enough. 



With the long and powerful ovipositor the mother insect intro- 

 duces her gggs into the tree, and there leaves them to be hatched. 

 As soon as it has burst from the eggs the young grub begins to 

 burrow into the tree, and to traverse it in all directions, feeding 

 upon the substance of the wood, and drilling holes of a tolerably 

 regular form. Toward the end of its larval existence it works its 

 way to the exterior of the trunk, and there awaits its final change, 

 so that when it assumes its perfect form it has only to push itself 

 out of the hole, and so finds itself in the wide world. The in- 

 sects may often be seen on the lirunks of the trees, clinging to the 

 bark close to the hole out of which they have emerged. Saw- 

 yers frequently destroy the grubs while they are cutting trees 

 into planks, but as many of the larvse escape the saw, th^y re- 

 main in the boards, and afterward emerge in houses, to the great 

 consternation of the inmates. Should such a circumstance occur 

 in the house of any reader of this book, he may at once infer that 

 the wood from which the insect escaped was not properly season- 

 ed. I have known the Sirex to be so numerous that it has fairly 

 driven the inhabitants out of their rooms, for it has a very fero- 

 cious appearance, and, on account of its long ovipositor, is always 

 thought to be armed with a venomous sting of peculiar potency. 



Two species of Sirex inhabit this country. In general appear- 

 ance they are very similar to each other, but the species just men- 

 tioned is nearly twice the size of its relative. They inhabit simi- 

 lar localities, and I have now before me a piece of a fir-tree in 

 which are the holes of both species. These insects are not only 

 interesting in their habits, but they furnish many beautiful ob- 

 jects for the microscopist. 



In the accompanying illustration, we have three excellent ex- 

 amples of wood-boring insects. In the centre of the drawing is 

 seen a portion of a tunnel, which is completely hollowed out, and 

 divided into cells. This is the dwelling which is constructed by 

 the splendid South African Carpenter Bee {Xylocopa Capensis), 

 a wood-borer of great power. She sets about her work in a curi- 

 ously systematic manner, each action being exactly calculated, 

 nothing left to chance, and all useless labor saved. 



When the insect has fixed upon a piece of wood which suits 

 her purpose, usually the trunk or branch of a dead tree, an old 



