SOME WOOD-BORING INSECTS 



387 



and timbers of houses. Generally the materials infested 

 are badly damaged by the small exit holes of the beetles, 

 and in many cases the inside of the wood is eaten away 

 and reduced to a fine dust-like powder. In other in- 

 stances the timbers may be so weakened as to become 

 positively unsafe and a menace to human life. Hopkins 

 says, " We have evidence of a 

 railroad wreck in which many 

 lives were lost, due to powder- 

 post injury to the principal 

 construction timbers." 



Davis reports finding a 

 species of these beetles, Lyctus 

 striatus injuring a red oak 

 floor in a college hall. The 

 beetles issued from the sap 

 wood only and were probably 

 feeding there when the floor- 

 ing was manufactured, at least 

 two years before. In the fall 

 of 1891 Webster found the 

 same species injuring the 

 floors and posts that sup- 

 ported the floors in the shops 

 of a certain manufacturing concern in Ohio. He was 

 able to trace the origin of the beetles to some oak 

 lumber that had been piled in the yards for the purpose 

 of seasoning it. When the wood had been taken into 

 the shops to work it up, the beetles had been carried 

 with it. The insects apparently were injuring only the 

 sap wood of the floors and posts. Pettit has found 

 the beetles working in finished oak and maple woodwork 



