White spruce and balsam fir targeted; now is the time to protect landscape trees from damage
Over the past few years, white spruce and balsam fir have been defoliated by the spruce budworm, one of the most destructive native insects in the northern spruce and fir
forests of the eastern United States and Canada.
“This year, budworm defoliation is widespread and expected to be heavy for the second or third years in many areas,” said Bob Heyd, forest health specialist with the Michigan Department of Natural Resources in Marquette.
Periodic outbreaks of these insects are a part of the natural cycle of events associated with the maturing of balsam fir and white spruce.
Spruce budworms overwinter as tiny caterpillars which disperse by dropping from treetops on webs. As new tree growth expands in the spring, the caterpillars grow and feed on new shoots. Budworms produce one generation each year.
Repeated budworm defoliation can cause top-kill and tree mortality in older and stressed trees. Balsam fir older than 60 and spruce over 70 years old provide prime infestation opportunities. Read more