By MELISSA HART

Michigan Correspondent

LANSING, Mich. — Forest tent caterpillars are making a comeback in the eastern Upper Peninsula and across the Lower Peninsula of Michigan.

According to Scott Lint, forest health specialist with the Michigan Department of Natural Resources’ Forest Resources Division, the insects are native to Michigan and occur in widespread outbreaks every 10-15 years.  The most recent outbreak peaked in 2010 and they are showing up again and taking down trees, one bite at a time.

While an infestation of forest tent caterpillars is rarely fatal unless a tree has other stresses, they can easily strip one of its foliage. “The larvae begin feeding on new leaves in spring, and can strip the leaves from a tree,” Lint said.

Defoliated trees will respond with a second flush of leaves in early July. The second growth is often stunted and brownish in color and further depletes the trees’ stored energy reserves. Adults are reddish brown with two brown, transverse-parallel bands. Larvae have long silky hairs on their body and a row of elongated spots along the back.

Also known as armyworms, these pesky insects do not actually form a tent, but they spin silken threads and mats on the upper trunk of the tree. The caterpillars will gather in large colonies when at rest or during periods of molting. As they increase in size, they will move lower on the tree.

While the forest tent caterpillar does have natural diseases, predators and parasites, physical control of the colonies can be done by removal of larvae from trees and removal of egg masses when detected while pruning. Economic infestations can be controlled by the use of a broad-spectrum insecticide.

Lint recommends that homeowners with trees that have been heavily defoliated should make sure those trees receive at least 1 inch of water per week during the growing season. Applying a slow-release tree fertilizer in the fall also will help trees recover quickly and prepare them for any defoliation that might occur next summer.