Look for egg masses
If you live in a quarantined county, survey your property for gypsy moth 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 gypsy moths are 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 gypsy moth, Ooencyrtus kuvanae, attack eggs of the gypsy moth.