SB 

 818 

 C578 

 ENT 



Circular No. 156. issued July 13, 1912. 



United States Department of Agriculture, 



BUREAU OF ENTOMOLOGY. 

 L. O. HOWARD, Entomologist and Chief of Bureau. 



INSECT DAMAGE TO MINE PROPS AND METHODS OF 

 PREVENTING THE INJURY. 



Bj- T. E. Snyder, 

 Agent and Expert, Forest Insect Investigations, 



INTRODUCTION. 



Wood-boring insects are one of the principal causes of the deterio- 

 ration and destruction of timbers used in mines. The injury is 

 effected both before and in some cases after placement in the mine. 



This circular is based on special investigations in cooperation with 

 mining companies. It is intended to give preliminary information 

 on the principal types of insect injury and to show how a large per- 

 centage of injury can be prevented. 



In recent publications ^ of this bureau genei'al information is given 

 on methods for the prevention of injury by in.sects to forest products, 

 including mine props. Several of these methods have been adapted 

 to the need of preventing injury to this special class of product, and 

 are included in the present circular. 



INJURY TO UNBARKED, ROUND, AND SPLIT PROPS BEFORE PLACEMENT IN 



THE MINE. 



Both soft and hardAvood timber, which has been felled for mine 

 props, and unbarked props that have been cut and left lying stacked 

 in the woods or in the yard at the entrance to the mine, are liable to 

 infestation with the grubs or larvae of wood-boring insects. These 

 grubs, which hatch from eggs deposited by winged insects attracted 

 by the odor of the fresh-cut timber, continue to work in the props 



^ Insect Depredations in North American Forests. (Bui. 58. Part V, Bur. Ent., U. & 

 Dept. Agr., 1900.) Insect Injuries to Forest Products. (Cir. 128, Bur. Ent., U. S. Dept. 

 Agr., 1910.) 



42055"— Cir. 156—12 



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