DEFECTS IN TIMBER CAUSED BY INSECTS 



In order to accomplish this saving it is necessary for manufac- 

 turers of wood products to utilize all available information that 

 has been obtained from experiments carried on for many years by 

 the Bureau of Ento- 

 mology, especially the 

 results of scientific re- 

 search on the specific 

 causes of the differ- 

 ent types of insect 

 defects and methods 

 of preventing them. 

 Data contained in 

 earlier bulletins by 

 experts of this bu- 

 reau, as well as new 

 and unpublished data, 

 have been used freely 

 in this bulletin. The 

 published articles by 

 Hopkins (23, 24, 25, 

 26, 27, 28, 29, 30, 31, 

 32, 33, 34, 35), Burke 

 (6,7), Webb (50,51), 

 Craighead (9, 10, 11, 

 12, 13, 14), Snyder 



(43, 44, 45, 46, 47), 



and St. George (41) 

 were the source of 

 much information. 

 The pioneer investi- 

 gations and publica- 

 tions of Doctor Hop- 

 kins, former forest 

 entomologist of the 

 Department of Agri- 

 culture, in reality 

 form the basis for 

 this bulletin. Doctor 

 Hopkins's investiga- 

 tions have done much 

 to prevent waste and 

 losses due to insects. 

 References to these 

 and many other pub- 

 lications are to be 

 found in Chamber- 

 lin (8). 



Timber inspectors 

 and graders should be 

 able to determine from the defect in the wood whether it was 

 caused by insects working in (1) the living tree; (2) the freshly 

 felled, green saw log or bolt, with or without the bark on; (3) the 

 green, unseasoned lumber; or (4) seasoned rough or finished product. 



Fig. 1. — Black 

 columhianus. 



holes in white oak 

 A, slightly enlarged ; 



made by CortJiylns 

 B, slightly reduced 



