WOOD-BORING INSECTS. 183 



of a tolerably regular form. Towards the eud 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 insects may often be seen on the trunks 

 of the trees, clinging to the bark close to the hole out of which 

 they have emerged. Sawyers frequently destroy the grubs while 

 they are cutting trees into planks, but as many of the larvae 

 escape the saw, they remain in the boards, and afterwards 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 seasoned. 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 ferocious 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 

 mentioned is nearly twice the size of its relative. They inhabit 

 similar 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 

 objects for the microscopist. 



In the accompanying illustration, we have three excellent 

 examples 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 Caepenter Bee 

 {Xylocopa Gapensis), a wood-borer of great power. She sets 

 about her work in a curiously systematic manner, each action 

 being exactly calculated, nothing left to chance, and all useless 

 labour 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 

 post, or a piece of wooden railing, she bores a circular hole about 

 an inch and a half in length, and large enough to permit her to 

 pass. Suddenly, she turns at an angle, and drives her tunnel 

 parallel to the grain of the wood, and makes a burrow of several 



