Although postspray reduction in egg masses is the standard measure used to evaluate control of the gypsy moth, Porthetria dispar (L.), the method does not provide for observation of treatment effects, or the detection of a mortality not related to treatment. Correlation analyses of egg-mass reduction with spray deposit, mortality among larvae caged with sprayed foliage, 10-minute live larval counts in the field, frass collections, and defoliation readings showed that the 3 last mentioned were significantly correlated with postspray egg-mass deposit.