388 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1941 



Definite recommendations are made for treating the predominant 

 stands of the regions, namely, coniferous plantations, coniferous un- 

 derstories, mixed conifers and hardwoods, and mixed hardwoods of 

 commercial importance. The writers conclude : 



Consideration of the history of the gypsy moth and of existing forest conditions 

 in New England leads to the conclusion that, in spite of all control effort to date, 

 epidemic outbrealjs with serious defoliation may continue to occur within the 

 infested area. 



Increasing the proportion of woodland in which conditions are unfavorable for 

 the development of the insect should lessen the need for artificial control and 

 reduce the frequency and severity of outbreaks. * * * With few exceptions, 

 elimination or reduction of highly favored food species will conform to desirable 

 silvicultural practices. Silvicultural control, therefore, has the added advantage 

 of serving the objectives of forest improvement. 



An introduced insect may thus prove to be the dominant factor in 

 shaping plans for the management of large areas of New England 

 forest land, provided our present appraisal of its economic importance 

 has not been too pessimistic. 



A dominant factor in shaping cultural practices for white pine in 

 the Northeast has been the white pine weevil. As farm lands were 

 abandoned a generation or more ago, they seeded in to stands of white 

 pine. In addition many acres were planted. Gradually it dawned on 

 the landowners and foresters that many apparently vigorous stands 

 were worthless "cabbage pines" as the result of repeated attacks of 

 the white pine weevil. The many desirable characteristics of this 

 tree, particularly its rapid growth and high-quality wood, led to 

 repeated investigations of the weevil problem, cuhninating in recom- 

 mendations by the Bureau of Entomology and Plant Quarantine, the 

 New York State College of Forestry, and Harvard Forest for growing 

 mixed stands of hardwoods and pine to avoid weevil damage (Mac- 

 Aloney, 1932) and for the reclamation of merchandise boles from 

 badly weeviled stands. (Cline and MacAloney, 1931, 1933, 1935.) 



Continued experimental work on the Harvard Forest tracts with 

 pines planted among hardwood seedlings was recently verbally re- 

 ported to the writer by A. C. Cline, director of Harvest Forest, indi- 

 cating simplified measures of growing these mixtures to avoid weevil 

 damage (pi. 8, fig. 2). It is obvious that white pines of value cannot 

 be grown commercially in the Northeast unless these methods or sub- 

 sequent modifications of them are utilized. 



Dying white and yellow birch in overmatured stands or following 

 logging operations or severe droughts have invariably been found 

 infested with the bronzed birch borer {Agrilus anxius Gory) in the 

 Northeast and in the Lake States. Studies of this insect (Hall, 1933) 

 have led to the conclusion that "changes in the physical factors of the 



