Parks Canada says guests flocking to the Rocky Mountains for the annual viewing of larch colours may be disappointed this year. Staff at both Banff and Yoho National Parks say an infestation of larch needleworm, a native moth whose caterpillars voraciously feed on larch needles resulted in “severe defoliation of larch trees” in both parks. “Affected trees may appear reddish brown, scorched or sparse and won’t be their characteristic golden-yellow colour this fall,” Parks Canada said in a statement. “While it may look alarming, the trees are expected to survive. Parks Canada continues to monitor the outbreak and assess what, if any impacts the trees experience.” The most affected area in Banff National Park is between the Sundance and Bow mountain ranges, between Healy Creek and Lake Louise. That region includes popular larch viewing trails such as Healy Pass, Taylor Lake and many others in and around Moraine Lake and Lake Louise. In Yoho, the most heavily affected area is in and around Lake O’Hara. According to Natural Resources Canada, the damage caused by larch needleworm is usually early enough for the tree to recover new needles before winter, but those are usually shorter than normal ones. There are no control measures in place, given the small size of the affected areas and the fact that infestations are limited to a short period of time.
