THUNDER BAY — Spruce Budworm, which causes severe damage to fir trees, is overdue for a big rebound in Northwestern Ontario, but its advance this year may have been slowed by hot weather last year. Although there are reports of impacted tree stands around the Thunder Bay area, “it’s a bit of a surprise” there hasn’t been more defoliation from the spruce budworm, said Taylor Scarr, director at the Great Lakes Forestry Centre in Sault Ste. Marie. The Eastern Spruce Budworm feeds mainly on balsam fir and white spruce, and to a lesser extent on red spruce and black spruce. Trees typically die after four or more years of severe defoliation. …The MNR doesn’t consider the current extent of the budworm infestation in the Northwest to be enough to warrant mitigation measures like insecticide. Large outbreaks tend to occur every 30 to 40 years – the last big outbreak was in the 80s.