10 THE GIPSY MOTH AS A FOREST INSECT. 



To a large extent tlie European, and particularly the German, 

 forests differ radically from those within the area infested by the 

 gipsy' moth in America. Oak, so common as a coppice growth in 

 America, is relatively little grown in Germany, and when successfully 

 grown- the forest bears httle resemblance to the typical American 

 coppice. It has been stated reix^atedly that oak is not materially 

 hajured ])y the gipsy moth in Germany, even tliough the trees are 

 occasionally stripped, because they refoliate and seem to retain a 

 fail' amount of vigor. Notwithstanding tins statement they are fre- 

 quently in bad condition, particularly hi forests wliich more nearly 

 approximate m character the American coppice. For example, in a 

 large tract near Neusalz-Oder many oaks were dead or dying. Various 

 causes were adduced for their death, such as attack by a species of 

 Agrilus, attack by a fungous .disease, attack by a leaf-roller, Tortrix 

 viridiana, etc., and the circumstance tliat they had been defoliated 

 several years before by the gips}' moth was not considered as respon- 

 sible for their condition. Itf is significant, and suggestive of the 

 existence of a parallel, that f9llo^\•ing defoliation by the gii)sy moth 

 ■in America the trees frequently refoliate, but are subsecpiently 

 destroyed by a species of Agrilus, or by a fungous disease, or by 

 something else than simply dejfoliation. 



Oak m Germany is aj)t to become stag-headed — that is. to die pre- 

 maturely from the top; and it also liappens frequently in America 

 that when trees have been otiice or twice defoUated by the gipsy 

 moth and then protected from further injury they are affected in 

 the same wav. In America We hav(^ l)een able to determine and 

 define the cause of the mjury through a comparison of conditions 

 outside and inside the infested territory. l)ut in Germany, where the 

 entire country may be said to l)e infested, such comparison is not 

 so easy. 



There are numerous other points which might be brought forward 

 in support of the contention that in Europe the liability of certain 

 types of forests to serious mjury through occasional defoliation by 

 the gips}^ moth has long been taken into account and tliat, albeit 

 unconsciously, methods of forest management have \yocn modeled 

 accordingly. Without attempting to reason out the whys and 

 wherefores the pioneer foresters were content to recognize the simple 

 fact that certain types of forests miglit not be grown under certain 

 conditions or at all, and whether this were due to the cliaracter of 

 the soil, or to tlie climate, or to the presence of an insect Uke the 

 gipsy motli matters not. 



Similar recognition of similar drawbacks to the cultivation of cer- 

 tain types of forest is })robably what we must come to in America. 

 It stands forth as the main result of tlie European observations that 

 in the European forests the gipsy moth is held in check by three 



