Outbreak history in Wisconsin

The first record of a tent caterpillar outbreak dates back to the 1600’s, and since then outbreaks have occurred on irregular intervals. This means our forests have evolved with caterpillars. Forest tent caterpillars are a natural part of the beautiful Wisconsin northwoods.

The most recent outbreak in northern Wisconsin began in Langlade County in 1986. After defoliating hundreds of thousands of forested acres, the population collapsed in 1991.

Another outbreak in Northern Wisconsin began in 1999 as scattered pockets of heavy defoliation of hardwoods. In 2001, forest tent caterpillars caused a heavy defoliation on many broad-leaved trees and shrubs throughout northern Wisconsin, especially Ashland, Bayfield, Iron, Price, Vilas, Oneida and Lincoln Counties.

Maps to show the area of defoliation caused by the forest tent caterpillar:

• 1987
• 1988
• 1989
• 1999
• 2000
• 2001