334 BOARD OF AGRICULTURE. [Pub. Doc. 



eradicate the favorable moth food. This year a special depart- 

 ment was inaugurated to carry on this work under a trained 

 forester. 



The various means of controlling the moths may be classified 

 under three heads, — direct entomological methods, indirect 

 entomological methods and forestry methods. The direct ento- 

 mological methods seek the destruction of the moths in 'one of 

 their various forms by human agency, as in spraying or creosot- 

 ing. The indirect methods seek the propagation of parasites 

 or disease which will destroy the moths. The forestry methods 

 seek the encouragement of tree growth which is unfavorable to 

 the moths. 



It has been found, from our own and from European observa- 

 tions and experiments, that although it will eat practically all 

 kinds of vegetation, the gypsy moth thrives only on a limited 

 number of species of trees. These trees, which are the oaks 

 (especially the white oak), willow, fruit and cherry trees, and 

 probably the gray birch, may be called "non-resistant" trees. 

 Unless a large proportion of their food consists of the leaves of 

 these "non-resistant" trees, under ordinary conditions the 

 moths will soon pass on to a more favorable feeding ground or 

 die. Therefore forestry methods, rather than attempting to 

 destroy the moths themselves, would destroy their food. If we 

 grow forests of resistant species, as conifers, maple, chestnut, 

 ash, etc., the moths will cease to be destructive. 



To shade trees and to ornamental or park woodland, where 

 hardly a tree can be spared, these forestry methods do not 

 apply very extensively, but in wild woodland spraying is too 

 expensive and other methods are costly or inefficient, and we 

 must rely on parasites, disease and resistant forest conditions 

 if we are to control the moths. This is the way they are con- 

 trolled in Europe, where they have existed from time imme- 

 morial, and this is the way we must eventually control them 

 in this country. It is a vast work, the changing the forest con- 

 ditions of this State, but if we can change the poor oak forests 

 into pine forests, for which most of the land is naturally suited, 

 the gypsy moth will turn out a blessing in disguise. 



The white oak seems a doomed tree in the moth-infested 

 region. Weakened by moth attacks, the "agrilus," or chestnut 



