For the first time, an invasive insect called the green alder sawfly (Monsoma pulveratum) has been found in Sitka. This insect is considered a danger to alder trees in Sitka and other Southeast wetlands.
“Several days ago a positive identification has been made on the green alder sawfly in Sitka,” Bob Gorman, resource development faculty with the Sitka office of the University of Alaska Fairbanks Cooperative Extension Service, wrote in an e-mail sent to Sitka and Southeast gardeners, “This invasive, exotic insect has defoliated alder trees in Anchorage and surrounding areas. It is a potentially serious threat to alder in southeast Alaska. The attached fact sheet (linked at the bottom of this post) provides details on the green alder sawfly. Distribute this information as you see fit. Thanks.”
The green alder sawfly is native to Europe and North Africa, and its preferred diet is European gray alder. It was first reported in North America in 1995 in Newfoundland, Canada. In 2004 it was first collected in Alaska near Palmer. Since 2007, the green alder sawfly has been documented defoliating thin-leaf alder (Alnus glutinosa) in numerous locations in Southcentral Alaska, eliminating alder in some watersheds. The green alder sawfly has been found in red alder (Alnus rubra) trees along Sawmill Creek Road, Halibut Point Road and Jarvis Street.
On Friday, KCAW-Raven Radio aired a story about the green alder sawfly with more details from Gorman and USDA Forest Service entomologist Liz Graham, who flew to Sitka from Juneau after Gorman sent her photos of the insect’s caterpillars.
Please report any known or suspected infestations of green alder sawfly to the Sitka office of the UAF Cooperative Extension Service by calling 747-9440 or stopping by the office located in Room 122 at University of Alaska Southeast Sitka Campus. GPS (global positioning system) coordinates of known locations of the green alder sawfly will help in determining the extent of this insect, which probably overwintered in Sitka.