190 THE GYPSY MOTH. 



winter. Objections to its removal based on this belief are 

 obviated by scraping in the spring before the opening of 

 the leaves, when the tree no longer needs protection against 

 the cold. If the loose bark of apple trees is scraped off 

 about April 15 and caught upon cloths spread beneath the 

 trees and the scrapings afterward burned, many injurious 

 insects are likely to be destroyed. 



FIG. 27. Long handled scraper. FIG. 28. Bark shave. 



If we go further, and without cutting too deeply remove 

 some of the outer bark, double benefit to the tree ensues.* 



Its growth is stimulated, a great flow of crude sap occurs, 

 a luxuriant growth of foliage is thrown out and an unusual 

 supply of elaborated sap for the upbuilding of the tree is 

 returned from the foliage and flows into the liber or inner 

 lining of the bark, killing or driving away the bark borers 

 (scolytidm) . These beetles are among the most dangerous 

 enemies of trees. For bark cutting a shave (Fig. 28) in- 

 vented by Mr. G. W. McKee, one of the special inspectors 

 employed by the Board, has been found very effective. 



Dr. Packard says that perhaps the best method of pre- 

 venting or stopping the work of bark beetles is that of a 



Elms which have had the outer bark removed in this manner in November have 

 developed an unusually vigorous growth of dark green foliage in the ensuing sum- 

 mer. Trees treated in this manner have shown great vigor also in healing wounda 

 oil their trunks. 



