UNITED STATES 



DEPARTMENT ok AGRICULTURE 



DEPARTMENT CIRCULAR 411 '''/ 



Septembet, 1927 



Washington, D. C. 



THE RELATION OF INSECTS TO SLASH 



DISPOSAL 



Prepared by the Division of Forest Insect Investigations, Bureau of Entomology * 



CONTENTS 



Page 



Slash a factor in forest protection ._ 1 



Few species of trees involved 3 



Pine slash 4 



White pine in the Northeast 4 



Red pine and white pine in the Great Lakes 



region 4 



Western white pine in the northern Rocky 



Mountain region 5 



Sugar pine in the Pacific coast region G 



Western yellow pine 6 



JefTrey pine in California 8 



Lodgepole pine .- 8 



Page 

 Pine slash- Continued. 



Monterey pine in California 9 



The southern pines 9 



Spruce slash. 10 



Spruce in the Northeast 10 



Spruce in the Great Lakes region 10 



Engelmann spruce in the Rocky Mountain 



region 10 



Douglas fir slash 10 



Conclusions -__ 11 



Literature cited. 12 



SLASH A FACTOR IN FOREST PROTECTION 



Does slash from cutting operations increase the insect menace to 

 hving timber? Many times this question has been asked by foresters 

 and timbermen, but there has been little uniformity in the answers. 

 Considerable confusion has arisen as a result, and a great diversity of 

 opinion is found concerning the influence of slash upon insect out- 

 breaks. 



Tw^o widely divergent opinions are held by professional forest ento- 

 mologists in North America. In Canada, Swaine {10, p. 18; 11, y. 

 762; 12, p. 25; 13, p. 47; 14, V- 231; 15, p. 346)' and Hopping (6, 7) 

 advocate on entomological grounds the necessity of slash disposal as 

 a phase of forest protection. Workers in this country, Graham {2, 

 p. 44'^) J for example, almost unanimously take the opposite view^point, 

 that under present economic conditions slash disposal can not be jus- 

 tified on entomological grounds. Chamberhn {1, p. 23), however, 



1 This circular was prepared by entomologists and collaborators of the Division of Forest Insect Investi- 

 gations. Those primarily responsible for the information contained in the regional statements are as 

 follows: F. C. Craighead, northeastern and southeastern forest regions; S. A. Graham, Lake States region; 

 J. C. Evenden, northern Rocky Mountain region; W. D. Edmonston and F. C. Craighead, soutnern 

 Rocky Mountain region; J. E. Patterson, north Pacific region; J. M. Miller, H. E. Burke, and H. L. 

 Person, California region. F. P. Keen and Y. C. Craighead are largely responsible for assembling the 

 paper as a whole. In making reference to this circular it is to be understood that it is a product of joint 

 authorship, as explained in the foregoing. 



2 Figures in italic in parentheses refer to "Literature cited," p. 12. 



31991°— 27 1 



