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 Cole (historian) Print". They divorced in 1983. Cole later married Christine Mullins. Cole's papers are held at the Simon Fraser University archives as the "Doug Cole fonds". Douglas Cole (historian) Douglas Lowell Cole (9 December 1938 – 18 August 1997) was an American-Canadian historian. Cole specialized in the art and culture of the Northwest Pacific Coast, and from 1966 until 1997 served as a professor in the history department at Simon Fraser University. Douglas Cole was born at Coulee Dam, Washington. His father was a construction worker and labor union activist. His mother taught elementary school. In 1960 Cole earned his bachelor's