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Circular No. 55. 



United States Department of Agriculture, 



DIVISION OF ENTOMOLOGY, 

 L. O. HOWARD, Entomologist. 



POWDER-POST INJURY TO SEASONED WOOD PRODUC TS. 



By A. I). Hopkins, 

 III ('li((r(je of Forest Insect Investigations. 



INTRODUCTION. 



The so-called powder-post injury to seasoned wood has attracted 

 much attention in America, and especially in Europe for centuries, and 

 has been the subject of published articles in many languages. 



This peculiar injurj' seems to be on the increase in the United States 

 and numerous requests from a number of the principal manufacturers of 

 vehicles and wooden articles have recently been addressed to this office 

 for information. The subject has received considerable attention 

 through Mr. F. H. Chittenden and the writer in the past, and investi- 

 gations are now being made with a view to publishing a special bulletin 

 giving detailed information. It is deemed advisable, however, to issue 

 this circular in advance, as it is addressed especially to our correspond- 

 ents who are in need of immediate information. 



CHARACTER OF POWDER-POST INJURY. 



Fine, flour-like powder is found on or beneath piled or stored hick- 

 ovy, ash, oak, and other seasoned hardwood products. Upon closer 

 examination small holes will usually be found in the surface of the 

 wood from which the powder will fall when moved or jarred, \ly cut- 

 ting into the wood, or splitting it, the interior is often found converted 

 into a mass of closel}^ packed material which readily crumbles into 

 powder. This is held together by an outer thin shell and intervening 

 libers of sound wood. It will also be found that the injury is confined 

 to the white or sapwood, and that the darker-colored heartwood is sel- 

 dom, if ever, thus affected, 



CHARACTER AND EXTENT OF LOSSFS. 



This form of injury is widely distributed over the world, and unless 

 remedies are instituted the resulting loss will be great. This is espe- 

 cially so in a country like the United States, which is rich in hard- 

 wood forest resources, and where there are extensive interests in the 

 manufacture of commercial products from such wood. It is a character 

 of loss which falls directly on the dealer, the manufacturer, or owner of 



