The citrus longhorn beetle (CLB), Anoplophora chinensis, was first discovered in Washington State in August, 2001, on a shipment of bonsai trees. Three adult beetles were found on the bonsai trees at a nursery in Tukwila, WA - but 5 more were observed flying away. Native to Asia, this beetle attacks over 40 species of hardwood and fruit trees - even healthy trees are usually killed. View information about CLB or additional photos. CLB is closely related to the Asian longhorned beetle (Anoplophora glabripennis), another invasive species that has caused extensive damage in Chicago and New York City.
The Washington State Department of Agriculture (WSDA) soon imposed a one-half mile quarantine around the site where CLB was first discovered. No potentially infested plant material could be moved out of the quarantined area except by special permit. Many residents took advantage of free monthly "chipper days" at the local high school, and developers were required to chip trees and stumps on site. The quarantine remained in place from November 2001 to December 2006.
WSDA also coordinated an extensive tree removal / treatment program in July and August, 2002. Nearly 1,000 trees located within one-eighth mile of the CLB site were cut and chipped, and another 1,500 trees located further away were treated with a systemic insecticide to kill CLB feeding on or within the trees.
Tree inspections conducted by WSDA began in the fall of 2001 and continued through 2006. No evidence of beetle infestation has been found since the fall of 2002.
Much of the information on this webpage was provided by David R. Bridgwater, USFS-retired.
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This webpage was last updated on May 16, 2008.