A forest pest is any organism that adversely affects the functioning of forest trees. Exotic forest pests, which have been introduced into the United States from abroad, have been primarily insects and infectious microorganisms (for example, the gypsy moth and microorganisms that cause chestnut blight). Of greatest concern are exotic forest pests from temperate forests similar to those of the United States, such as in Europe, eastern Russia, China, Australia, New Zealand, and Chile. Much of the recent importation of logs, wood chips, and lumber from temperate forests has been into the Pacific Northwest, including Oregon, Washington, and northern California.