Four methods (light traps, foliage samples, canvas bands, and gypsy moth egg mass surveys) that are used to study the population dynamics of foliage-feeding Lepidoptera were compared for 10 species, including gypsy moth, Lymantria dispar L. Samples were collected weekly at 12 sites during a 15-wk period in 1995–2001. For each non–gypsy moth species, light trap and canvas band estimates were regressed against foliage sample to determine how well they predict population abundance. Gypsy moth estimates obtained from foliage and under canvas bands were compared with counts of egg masses using a similar linear model. All comparisons were made on three spatial scales: plot (200 ha), forest (2,000–3,000 ha), and study site (200,000 ha). Abundance of moths collected by light traps were good predictors of population size compared with counts of larvae on foliage, whereas mixed results were obtained for canvas bands. Both foliage samples and canvas band samples proved to be good predictors of gypsy moth population size on the plot and forest scale, although only foliage samples provided good estimates at the study site scale. For all comparisons, predictability of light traps and canvas bands increased with increasing spatial scale.