14 U.S. DEPARTMENT OF AGRICULTURE BULLETIN NO. 484. 
Blue beech, choke cherry, wild red cherry, hop hornbeam, ani 
sassafras have no particular commercial value, and the elimination 
of these species from stands would afford some degree of. protection. 
Black cherry has considerable commercial value, but occurs very 
scatteringly. As it is not a favored food, it may well be left in view 
of its value. American elm and slippery elm also occur as scattered 
trees. Their value is less than black cherry, but they might weii 
be left. Cottonwood, bitternut hickory, black gum, silver maple, 
and silver poplar if found might well be eliminated from mest 
stands. Such an elimination would help to reduce the complexity 
of stands and would serve as a protective measure. 
The remaining species of this class, black and yellow birch, mocker- 
nut, pignut and shagbark hickories, and red and sugar maple, can 
be grown in comparative safety. In any process of gradual trans- 
formation these species should be retained in preference to the trees 
of Class I. 
Class IV (p. 9) is composed of trees on, which the gipsy moth 
does not feed, or if it does, the amount is so slight as to be entirely 
negligible. Stands composed of trees of this class alone, or combined 
with the trees of Class II, need cause no anxiety whatever as far 
as gipsy-moth attack is concerned. Some of the species of this 
class are of rare occurrence, some require peculiar conditions for 
their development, and some have little or no commercial value. 
Arborvite, black ash, and white cedar require very moist situations 
and usually occur in or near swamps. Butternut, red cedar, locust, 
honey locust, and sycamore all require a large amount of light. The 
red ash, hackberry, American holly, red mulberry, tulip, and black 
walnut are of rare and local occurrence, for which reason they can 
not be depended upon to supply any large commercial demand. 
Flowering dogwood, mountain laurel, mountain maple, striped 
maple, and sheepberry have little or no commercial value locally. 
The white ash has a high commercial value, but should be confined 
to the best forest soils. | 
In general, it may be said that stands containing only trees of 
Classes II, III, and IV will suffer but slight damage from gipsy- 
moth attack. The number of Class I trees would be tremendously 
reduced if the worthless species were replaced by suitable trees and 
the remainder were confined to the best sites, as is necessary if they 
are to be grown at all profitably. 
Any plan for the removal of trees must provide for their replace- 
ment with more desirable ones. All trees may be removed in one 
operation and replaced in another, or the transformation may be 
gradual. There are many conditions which influence the methods 
to be employed, and these vary greatly among different stands. It 
is hoped that the experiments now in operation will provide a basis 
