Pine wilt is a disease characterized by sudden death. The needles remain attached, but become reddish brown. It is currently a major problem in Japan on Pinus thunbergii and P. densiflora. It was first identified in the U.S. in Columbia, MO in 1979. It is now known in 32 states on 20 species of pine, two of larch, two of spruce, two of cedar, and on balsam fir. The causal agent is a nematode, Bursaphelenchus xylophilus, transmitted by Cerambycid beetles. Ornamental plants of P. sylvestris and Christmas tree plantations of this species suffer damage. Forest trees of various species have also been found to have the disease. Some pine species are more susceptible than others. Although pine wilt is not a major problem in the U.S. it is potentially dangerous. The only practical control now available is removal and burning of dead trees.