INTRODUCED PESTS THAT ARE WELL ESTABLISHED 



Examples of introduced forest pests that have become estabHshed 

 in the United States are the European gypsy moth, balsam woollv 

 adelgid, and the fungi causing white pine blister rust, Dutch elm 

 disease, beech bark disease, and chestniu blight. 



European gypsy moth, the most serious pest of oak forest t\'pes, 

 was introduced into Massachusetts in 1869. Favored by the large 

 expanses of oaks and other host species in the Eastern United 

 States and a relative lack of natural enemies, it has since spread 

 and become established in all or portions of 16 Northern and 

 Mid-Atlantic States. The infestation has now reached into 

 Michigan, North Carolina, Ohio, Virginia, and West Virginia and 

 continues expanding westward and southw'ard at a rate of about 

 10 to 15 miles per year. Landowners and forest managers in the 

 path of the expanding infestation are experiencing its effects for 

 the first time. In areas infested for the first time, outbreaks tend 

 to persist longer and cause defoliation in several consecutive 

 years. As a result, tree mortality can be hea\y. Loss of trees affects 

 wildlife habitat, aesthetics, wilderness, recreation, and timber 

 productivity. The European gypsy moth feeds on more than 300 

 tree and other plant species, so its impact extends beyond oaks, 

 which are one of its favorite foods. Suppression of outbreak pop- 

 ulations is often necessary to protect high-value forests. Vast 



Oaks around this house in Pennsylvania were defoliated h\ 

 the European gypsy moth (photo © 1992 Xale Baron). 



16 



Forest Health Concerns 



