The Problem of the Sirex 



rest and ceiled with the aid of an adhesive 

 fluid which holds the fine sawdust of the stop- 

 per in place, is a thing of the present; it is 

 the nymphosis-chamber. 



A second Buprestis, Chrysobothrys chryso- 

 stigma, likewise an exploiter of the cherry- 

 tree, between the wood and the bark, al- 

 though more vigorous, expends less labour 

 on its preparations. Its chamber, with mod- 

 estly varnished walls, is merely an expanded 

 extension of the ordinary gallery. The 

 grub, disinclined for persistent labour, does 

 not bore the wood. It confines itself to hol- 

 lowing a slanting du^-out in the bark, with- 

 out touching the surface layer, through which 

 the insect will have to gnaw its own way. 



Thus each species displays special me- 

 thods, tricks of the trade which cannot be 

 explained merely by reference to its to'ols. 

 As these minute details have consequences of 

 some importance, I do not hesitate to mul- 

 tiply them : they all help to throw light upon 

 the subject which we are investigating. Let 

 us once more see what the Longicorns are 

 able to tell us. 



An inhabitant of old pine-stumps, Crioce- 



phalus ferus makes an exit-gallery which 



yawns widely on the outside world, opening 



either on the section of the stump or on the 



217 



