157 



used include two introduced European parasites, the braconid, Agathis pumita and 

 eulophid, Chrysocharis laridTullae. In western North America, however, biological con- 

 trol using Agathis fmmila was not satisfactory. Other parasites, including Chrysochans 

 landneUae, -were released from 1971 into Jhe 1980s (Ryan etal. 1987). Long-term studies 

 are under way to evaluate the effectiveness of the parasites (Ryan 1990). 



\aturat range of westfrn larch in thf Unitfd States 



European Larch Canker 



European larch canker disease infests species of the genus Larix and the Chinese 

 monotype. Pseudolanx amabilis. This disease is caused by a fungus, LachneUula {Das- 

 yscypha) unllkomnui, and was first reported in North America in 1927 (Spaulding and 

 Siggcrs 1927). The disease was effectively eradicated from Massachusetts by 1965 

 (Tcgcihoff 1965), but a new infestation was found in Canada in 1980 (Magasi and 

 Pond 1982). Subscquendy, infesutions were observed in the coastal areas of eastern 

 Maine (Miller-Weeks and Stark 1983). In those areas where the disease is present, the 

 canker has infested and damaged 50 to 100 percent of the larch in plantations or 

 young managed stands (USDA Forest Service 1991b). Tlie severe impact of the 

 canker on larch in parts of Europe and its potential impact on North American 

 species has prompted Environment Canada, the USDA Forest Service, and the Maine 

 Forest Service to issue public-information flyers urging extreme caution in transport- 

 ing cuttings and seedlings (USDA Forest Service 1991b). 



Pear Th rips 



Pear thrips {Taeniothnps income^turu) are native to Europe and were introduced to 

 North /Vmerica approximately in 1900 (c/ Carey et aL 1992). Tlie insect was first de- 

 scribed as a pest on fruit trees in California (Foster and Jones 1915), but recenUy has 

 become a serious pest of sugai maple (Acer saccharum) (Parker et al. 1988). Pennsyl- 

 vania foresters first observed defoliated trees in 1979, and pear thrips were identified 

 as the causal agent. A subsequent inspection of survey records indicated (hat pear 

 thrips were present in central Pennsylvania during the mid 1970s (Quimby 1990). 



Pear thrips infestations are found in New England and (he Great Lake States and are 

 spreading to the midwestern region. Scientists cannot yet explain why pear thrips. 



