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
Robert Douglas, Count of Skenninge and died without issue. The daughter married an Oxenstierna. The remaining son, Gustaf, was first of the Swedish-born noble line of Douglas. He became a Colonel and Governor of Västerbotten. The Swedish noble family of Douglas descends from him. His grandson, Count Gustav Otto Douglas, was captured by the Russians during the Battle of Poltava, entered Russian service, and in 1717 was made Peter the Great’s Governor General over Finland. In the 1890s the then head of the family, Count Ludvig Douglas, was the Swedish foreign minister and Marshal of the Realm. His father Count Carl Israel Douglas (1824-1898) had