190/.] 



\V< x >J> W'ASI'S. 



99 



seizing one another and rolling over and over. The size of the 

 insects and their humming sound are probably the foundation 

 for the old myth of their having invaded towns and attacked 

 the inhabitants. 



The larvae live in wood. They are whitish grubs with rounded 

 bodies, and have small horny heads with mandibles fitted for 

 gnawing. There are three pairs of stunted thoracic feet, and 

 the last segment ends in a horny spine of use to the larva in its 

 progression in the wood. 



Two genera are of interest in forestry ; the genus Sir ex and 

 the genus Xiphydria, which may be distinguished thus : — 



Sir ex. — The head is joined in ordinary fashion to the pro- 

 notum. Xiphydria, — The head is seated on a long neck-like 

 continual inn of the pronotum. 



nil STEEL BLUB WOOD WASP, Sirex THE GIANT wood WASP, Sirex 



(uvencuSi female.— (after cameron). gigas, male. — (after cameron). 



Tlu' lame of the genus Sirex live in the wood of coniferous 

 tn-es and have a far greater forest importance than those of 

 Xiphydria, which have been found in the wood of some broad- 

 leaved species. 



The Genus Sirex. 



Of this genus there are two spirits in Britain, Sirex iiiaas 

 the (iiant Wood wasp, and Sirex juvenens, the Steel-blue Wood 

 wasp. Neither is s<> rare as is generally stated. 



Sirex i;iziis. - The female may reach -including the ovipositor 

 — a length of i.J in., but it may be as little as an inch or even 

 less. This ditfere-nee in size is characteristic of wood-infest ing 



