136 TIMBERS AND THEIR USES 



wood, and their jaws are well developed to enable 

 them to do so. Some few attack living trees, 

 but, for the most part. Termites confine their 

 attentions to sleepers, telegraph poles, founda- 

 tions of houses and the like. So industrious are 

 they that they will reduce a good sized log of 

 wood to a fine powder in a single night. Their 

 depredations are dangerous, in that they often 

 eat away the interior of a piece of wood, leaving 

 but a thin husk without a sign of damage. The 

 first occasion on which such damaged wood is 

 subject to strain, collapse takes place, often 

 with disastrous results. In some parts of the 

 tropics anything and everything wooden is 

 devoured by these voracious creatures. For- 

 tunately a few woods are proof against their 

 attacks, mainly because of a high resin content 

 or, at any rate, the presence of some substance 

 which is distasteful to the insects. 



Beetles of the family Bostrychidce are also 

 highly injurious to timber ; their borings, to- 

 gether with those of the family Platypodidce, are 

 all too frequently to be found in tropical timbers 

 imported to this country. The wide, wormy 

 tunnels of many of the Bostrychids, and the 

 smaller, more numerous borings of the Platy- 

 fodids, not only render the wood unsightly but 

 seriously affect its strength. 



The familiar "worm-eaten" wood in this 



