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Editorial: Fight against caterpillars

It’s hard to like forest tent caterpillars. They can be a messy nuisance. They feed on the leaves of trees, and in rare instances, can weaken them enough to kill them.

And their numbers are climbing. The Minnesota Department of Natural Resources expects their population could be building to a peak in 2014 or 2015.

The DNR has some simple steps homeowners can take to naturally control forest tent caterpillars:

n Remove egg masses. Remove and destroy overwintering egg masses from branches of small trees before eggs start to hatch in the spring.

n Brush off or spray with water. Caterpillars and cocoons can be brushed off houses, picnic tables, or decks with a stiff broom or brush or knocked down with a forceful spray of water. Be careful not to crush too many caterpillars; they can smear and leave marks on some paints.

n Turn off exterior lights. Moths of forest tent caterpillars are attracted to lights. When moths are abundant, turn off exterior lights. This may reduce the number of egg masses laid on nearby trees.

n Build barriers. If you can determine that there are no egg masses in a tree or if you have sprayed the tree, you may be able to prevent migrating caterpillars from climbing up the trunk by the use of barriers.

n Enclose gardens. Although recommended by homeowners, this next method has not been scientifically proven. To protect an area (garden), build a 24-inch-tall enclosure of plastic sheeting and secure its lower edge to make sure that caterpillars can’t crawl underneath it. Spray the sheeting with vegetable oil to prevent the caterpillars from climbing the wall. Repeat oil application daily, or more often as needed.

Don’t forget about the natural strategies. They may require more time and elbow grease but will be a better approach for everyone.


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