Mike Hillstrom, forest health specialist, Fitchburg, Michael.Hillstrom@wisconsin.gov, 608-513-7690

Cherry scallop shell moth, a native defoliator, is back again in Jefferson and Walworth counties. Several residents recently reported large numbers of moths in areas that have experienced multiple years of defoliation by this insect.

Eggs laid by those moths are expected to hatch soon, and the emerging caterpillars will begin feeding on cherry tree foliage. Hopefully, populations of egg-parasitizing natural enemies will be high enough this year to provide relief to stressed trees.

Early instar caterpillars on cherry leaf.

Landowners in the area who have already noticed adult moths or witnessed defoliation in past years should begin checking their trees for caterpillars from July through August. Caterpillar signs include the tube-like nests they form out of webbing, tying the leaves together. To control the caterpillars, either squish them or remove and soak them in soapy water.

Caterpillars feed inside the nests formed by tying leaves together.

For more information on cherry scallop shell moth, see the USDA Forest Service publication.