FOOD PLANTS OF THE GIPSY MOTH IN AMERICA. 35 



In arranging the foregoing classes it was not easy in all cases to 

 assign a food plant according to this arbitrary classification. A 

 number of species such as the poplars and hickories belong near the 

 border line of Classes I and II, and they have been rated in the list 

 which seems most appropriate. In general it can be said that when- 

 ever any of the trees or shrubs in Class IV are growing together no 

 injury from gipsy-moth attack need be feared, and the same is true 

 of Class II, or a combination of Classes II and IV. In case any of 

 the species given in Class III are present there is a slight chance 

 of injury resulting, but for practical purposes no difficulty is likely 

 to be experienced by an owner so long as the species given in Class I 

 are not present in his woodland or on his private grounds. 



THE FOREST PROBLEM. 



An examination of these classes, however, shows that the species 

 noted in Class I are at present the dominant species in the wood- 

 lands in the area now infested with the gipsy moth. The oaks and 

 birches predominate over much of this area, and this increases the 

 difficulty of remedying the situation. 



It will be noted that most of the species of high commercial value 

 are included in Classes I and II. In arranging combinations which 

 will resist moth attack it is necessary to consider the soil and other 

 conditions suitable for their successful growth and to endeavor to 

 bring about replacements with the least possible expenditure of 

 money. 



The encouragement of coniferous growth is to be commended pro- 

 vided the Class I trees can be eliminated. Experimental work with 

 different stands of forest growth is being conducted by Mr. G. E. 

 Clement, of the Bureau of Entomology, and practical advice to 

 owners conveying the best methods of handling their wooded areas 

 is being furnished. 



It should be noted in examining the foregoing lists that, in addi- 

 tion to forest trees and shrubs, plants of much importance to hor- 

 ticulture and for ornamental and city planting are included. The 

 problem is therefore broader than that of managing forests, as horti- 

 cultural and shade-tree management should be adopted so that the 

 least injury will result from the moth and that the least expense in 

 controlling it will be necessary. 



RECOMMENDATIONS FOR ORCHARD PRACTICE. 



Among the horticultural crops most likely to be affected by the 

 gipsy moth is the apple. 



In moderate infestations the gipsy moth can be controlled by 

 spraying with arsenate of lead, used at the rate of 10 pounds to 100 



