Tent caterpillars in Wisconsin
The forest tent caterpillar is one of the major defoliating caterpillars in Wisconsin. It is distributed throughout the United States and Canada wherever hardwood trees grow. The populations of forest tent caterpillars periodically erupt, and cause heavy defoliation on broad-leaved trees and shrubs in Northern Wisconsin. During an outbreak, many caterpillars are found not only on trees, but also crawling on roads and buildings. Some people mistakenly call forest tent caterpillars “army worms” because when they migrate on the ground to find more food, they look like marching soldiers.
Update (June 2009): We have been receiving lots of inquiries about tent caterpillars this spring. Here is an update from DNR Forester Mike Schuessler:
The "tents" that you are seeing are from the Eastern tent caterpillar. The Eastern tent caterpillar is native to the US.
The Eastern tent caterpillar population is at or near its peak. They have a 7-8 year cycle and the population will crash soon.
They typically feed on the different types of cherry (pin, choke & black) and other ornamentals like crab apples. When preferred food is in short supply they will move to other ornamentals.
While they may be disturbing and unsightly, they typically cause little long-term damage to the trees they feed upon. Only during severe drought or if the tree has some major problems prior to the defoliation will it cause mortality.
Since the Eastern tent caterpillars are spring defoliators, the tree has plenty of time to re-leaf and restore their root reserves before winter.
If you have specific trees that you do not want to see defoliated take appropriate action to on those specific trees. You have a couple of reasonable options to protect individual trees.
Option 1: Remove those "tents" by hand and dispose of in a pail of soapy water.
Option 2: Cut the branch and scrape into a bucket of soapy water.
Option 3: Spray tent with a soapy water mix.
Do not take extreme measures (i.e. gasoline, fire, or broad-band insecticides). Broad-band insecticides kill bees and other beneficial insects.
Use "tangle foot" (available from a lawn and garden store), a sticky substance that keeps the caterpillar from climbing up the tree, on trees that are not infected.
Hope this helps - in a few weeks all that will remain is a few empty "tents" and a newly leafed out tree.
If you have more questions, please contact us:
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