September

Look for egg masses

If you live in a quarantined county, survey your property for spongy moth (Lymantria dispar) egg masses. Look for egg masses in crevices and protected hiding spots on rough bark, the undersides of branches, under signs attached to trees, and even on buildings, play equipment, benches, and picnic tables.  Conducting a thorough survey on your property can help determine if spongy moth is likely to cause significant defoliation next spring (instructions here).

New egg masses are firm to the touch. Old ones are pale in color, will crush easily, often look tattered and are not of concern.

Hold off treating or removing egg masses until after the first hard frost to let a natural enemy of the spongy mothOoencyrtus kuvanae—attack the egg masses.

Examples of a new, fresh egg mass (left) that caterpillars will hatch from next spring and an old egg mass from last year that is already empty (right)
Photo Credit: Bob Queen, WI DNR.