68 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 10 



given much consideration as a borer protector. For the screening 

 only, the cost would range from one cent for a two-year-old tree, to 

 about six or seven cents for a 12-year-old tree. 



In these tests, screening was so applied that it would stand out 

 all around the tree. A few strands of the wire were pulled out along 

 one edge and the free ends were then passed through the other edge 

 of the screening and bent over, thus securely locking the protector 

 around the tree. The screening was then crimped around the top 

 and securely fastened to prevent adults from entering. 



At the end of the first year it was noticed that the screens were 

 rusted out below the surface of the ground. Were it not for this, 

 it would seem that screening would last at least three years. It was 

 found, moreover, that the screening had to be readjusted each year. 

 Another objection against screening was the fact that a tendency to 

 girdle the trees readily developed when screens were tightly fastened 

 around the top. 



Examination of 133 screened trees showed that only two were 

 infested in 1915, thus representing a control of 85.9 per cent. In 

 the second year, 15 were infested and the control was only about 

 51.3 per cent. In the case of the infested trees, it seemed that beetles 

 must have deposited through the meshes at a point whfere the screen- 

 ing happened to touch the trunk of the tree. Other cases, trees were 

 infested when there was no means of accounting for how the beetle 

 could have deposited its egg in the tree. 



Conclusions: 1. That the cost of screening makes it prohibitive 

 as a protector. 



2. The danger from girdling is another factor against its use. 



ASPHALTUM 



After investigation, it was thought that asphaltum might hold 

 some promise as a borer protection, provided that it did not injure 

 the trees and it was sufficiently permanent not to require much re- 

 touching. It was found that two pounds of asphalt were required to 

 cover a twelve-year-old tree, and that one pound would cover about 10 

 two-year-old trees. 



In 1912, some prehminary tests were made on twelve-year-old 

 trees. Results indicated that where the asphalt covered the bark it 

 caused a tendency for excessive deposits of cork to form. The trouble 

 did not appear to be due to the heat of application, because in this 

 case the Hving tissue would have been killed in places. It was thought 

 that trouble might have been augmented at least by heat which might 

 have been absorbed on account of the black color of the asphalt. 

 This seemed improbable because the injury was no worse on the south, 



