Forest health staff from the Michigan Department of Natural Resources are currently working on mapping out the extent of the damage brought about by spruce budworm on white spruce and balsam fir in the northern Lower Peninsula and the Upper Peninsula.
The last time a widespread spruce budworm outbreak was recorded in Michigan was in the 1980s. With the insects active again, experts believe that a new epidemic is starting which will persist for the next several years. According to Bob Heyd, a forest health specialist for the DNR, most of the spruce budworm larvae are already done with feeding for the year. Some larvae may still be seen chewing on needles but most of them have transformed into pupae.
Budworms are some of the most destructive of native insects thriving in fir and northern spurce forests in Canada and eastern United States. Periodic outbreaks are a natural part of the life cycle of white spruce and balsam fir, with large-scale events typically occurring every 30 to 50 years.
Balsam fir trees in the area are always the hardest hit by budworms, 67 percent of which were killed during the last outbreak in the state. During that same time, just 42 percent of white spruce succumbed to the budworms.
Budworms feed every year, some areas were hit for the first time while others deal with related damage on and off for years. Insect activity for this year appears to be much more widespread, although the degree of damage varies from area to area.
While white spruce and balsam fir are its usual victims, spruce budworms also feast on tamarack, black spruce, hemlock and pine, most especially when these trees are in stands with the other two, although they suffer less damage overall.
Based on initial findings from the DNR, the areas hardest hit by spruce budworms this year are located south of the east-west line bounding north by Lake Michigamme in the Baraga and Marquette counties, western Upper Peninsula and on the east between Rapid River and Marquette by U.S. 41 in the Delta, Alger and Marquette counties.
"Eastern Mackinac and Chippewa counties, east of the Hiawatha National Forest, also have impacted areas. The southeast northern Lower Peninsula has also reported areas of heavy defoliation," said Heyd.
Spruce budworm outbreaks have been happening since 1909, typically lasting between 10 and 15 years. Millions of spruce and fir cords are lost each time an outbreak occurs, with the last outbreak affecting 519,000 acres of the trees in Michigan.
Photo: U.S. Fish and Wildlife Service - Northeast Region | Flickr
