THE EASTERN HEMLOCK. 

 Table 10. — Growth of hemlock in Otsego County, N. Y. 1 



27 



Age. 



Diameter breast-high. 



Height. 



Volume. 



Inches. 



Feet. 



Cubic feet. 



Board feet. 



Mini- 

 mum. 



Aver- 

 age. 



Maxi- 

 mum. 



Mini- 

 mum. 



Aver- 

 age. 



Maxi- 

 mum. 



Aver- 

 age. 



Maxi- 

 mum. 



Aver- 

 age. 



Maxi- 

 mum. 



Years. 

 20 

 30 

 40 

 50 



60 

 70 

 80 

 90 

 100 



110 

 120 

 130 

 140 

 150 



160 

 170 

 180 

 190 

 200 



0.1 

 .3 



.5 



.7 

 .9 

 1.1 

 1.3 

 1.5 



1.9 

 2.1 

 2.4 

 2.7 

 3.0 



3.3 

 3.7 

 4.1 

 4.4 

 4.9 



0.4 

 .9 

 1.4 

 1.9 



2.5 

 3.3 



4.0 

 4.7 

 5.5 



6.4 

 7.3 

 8.3 

 9.4 

 10.5 



11.6 

 12.7 

 13.5 

 14.3 

 15.1 



1.5 

 2.9 

 4.4 

 5.9 



7.4 

 8.9 

 10.5 

 12.1 

 13.8 



15.4 

 17.1 

 18.7 

 20.4 

 22.1 



23.9 



25.7 

 27.4 

 29.1 

 30.9 



5 

 6 



7 



8 

 9 

 10 

 11 

 13 



15 

 16 

 17 

 19 

 20 



22 

 23 

 25 



27 

 29 



7 

 10 

 13 

 16 



20 

 24 

 28 

 32 

 36 



40 

 45 

 50 

 54 

 59 



63 

 66 

 69 

 71 

 72 



17 

 28 

 39 

 49 



58 

 66 

 73 

 79 



84 



88 

 91 

 94 

 97 

 100 



102 

 105 



























1.7 



3.1 



5.0 



7.9 



11.1 



15.5 



20.0 

 24.0 

 29.0 

 34.0 

 39.0 



2.8 



6.4 

 11.4 

 18.1 

 26.0 

 36.0 



47.0 

 60.0 

 75.0 

 91.0 

 108.0 



126.0 

 145.0 











16 

 29 

 44 



61 

 80 

 100 

 120 

 140 



30 



55 



86 



120 



170 

 230 

 300 

 ■ 380 

 480 



590 



710 



850 



1,000 



1,150 



i Based on measurements of 176 trees, 48 to 420 years old, made by J. G. Peters in 1902. 



Table 11. — Growth of hemlock in Vermont. 2 

 (Average.) 



Age. 



Diameter 

 breast-high. 



Volume. 



Years. 



Inches. 



Bd.ft. 



130 

 140 



7.0 

 8.0 





34 



150 



9.0 



48 



160 



10.2 



69 



170 



11.4 



100 



180 



12.6 



140 



190 



13.9 



180 



200 



15.2 



230 



2 Data contained in Vermont Experiment Station Bulletin 161, "Hemlock in Vermont," by A. F. Hawes. 

 Volumes scaled by Vermont rule. 



SUSCEPTIBILITY TO INJURY. 



As before stated, hemlock is extremely sensitive to sudden changes 

 in the density of the forest. Middle-aged and full-grown trees appear 

 to be the most susceptible. 



The most destructive of the insect enemies of hemlock is the flat- 

 headed eastern hemlock bark borer, Melanophila fulvoguttata Harr. 

 According to Mr. H. E. Burke 3 this insect "has caused the death of 



3 "Injuries to forest trees by flat-headed borers." Yearbook of the Department of Agriculture, 1909; 

 pp. 405-406. See also following articles by Dr. A. D. Hopkins: 



"Catalogue of exhibits of insect enemies of forest and forest products, etc.," Bui. 48, Bureau of Ento- 

 mology, U. S. Department of Agriculture, 1904, p. 38. 

 " On the study of forest entomology in America," Bui. 37, Bureau of Entomology, 1902, p. 22. 



