Christmas tree pests and weeds of different pests, most of which cause cosmetic damage to the trees, important in the Christmas tree industry. The balsam woolly adelgid ("Adelges picae") are small soft-bodied insects which attack the Fraser fir. The insects appear as white, woolly spots on the tree and are fatal to the fir if left untreated. The woolly adeligid was native to central Europe where it affected the silver fir; it was introduced to the United States, where it has no known native predators, before 1900. Balsam twig aphids ("Mindarus abietnus") are another type of tree pest which affects fir and spruce trees in
Douglas Ranges flows along the southeast flank of the range. East of the Douglas Ranges, across Harrison Lake, are the Lillooet Ranges, while to the west and northwest are the Garibaldi Ranges. Southeast across the Fraser River is the Canadian portion of the Cascade Range. Because of the warmer climate (relative to the rest, even, of the British Columbia coastal lowlands), there were forests of immense trees throughout the Douglas Ranges, which were logged relatively early on in British Columbia's history. A network of logging railroads ran throughout the basin of the Chehalis River, which drains the core of the ranges to