INSECT INJURIES TO HARDWOOD FOREST TREES. 



317 



METHOD OK COMBATIM; TIIK INSECT. 



The fact that there is ;i single generation annually, and that the 

 generation* pass the winter in the immature stage in the bark, makes 

 it a comparatively easy pest with which to deal. It is only nores>ary to 

 determine which trees are actually infested at the beginning of winter, 

 and to see that those are cut and the bark burned before the middle of 

 the following May. If the greater number of infested trees over a 

 considerable area are thus treated, the number of the insects will be so 

 reduced that they can not continue their destructive depredations on 

 living trees. It is important to remember that there is nothing to be 

 gained by cutting and burning the old 

 dead trees after the insects have emerged, 

 but that it is of the greatest importance 

 to locate all trees which have died within 

 a year from the 1st of June and are 

 infested, and that these be cut and the 

 insects destroyed before the 1st of May 

 of the year following the death of the 

 tree. In some eases it will be advisable, 

 when the tops and branches only are dead 

 and infested and the remainder of the 

 tree is living, to cut out and burn the 

 infested top and thus save the lower part 

 of the tree. The broods can be de- 

 stroyed without loss of the wood by 

 utilizing it for fuel within the time 

 specified, or, if it is desired for other 

 purposes, the bark can be removed and 

 burned or the logs placed in water until 

 the insects are all dead. 



The practical application of this meth- 

 od of cutting and burning the infested 

 trees was made by the commissioner of 

 parks and boulevards of Detroit, Mich., 

 on Belle Isle Park, in May, 1903. A 

 great many hickories on the island were 

 infested, and all were threatened with 

 destruction by this insect. Upon request of the commissioner, 

 addressed to the Department of Agriculture, investigations were made 

 by the writer, who recommended that the infested trees be cut and 

 burned before the broods of the beetles commenced to emerge. This 

 plan was promptly adopted, and the cutting and burning of the 

 infested trees was so thorough that no evidence of the destructive 

 work of the beetle on the remaining trees has since been observed. 



FIG. 29. Exit holes in bark of hick- 

 ory tree from which broods of the 

 hickory bark-beetle have emerged. 

 (Original.) 



