Larvae of gypsy moth, Lymantria dispar (L.), were fed gypsy moth nuclear polyhedrosis virus on selected host plants to study influence of host plants on larval mortality. Larvae consuming the virus on red oak, Quercus rubra L., or red maple, Acer rubrum L., showed significantly lower mean mortality due to the virus than did larvae fed virus on quaking aspen, Populus tremuloides Michx., or pitch pine, Pinus rigida Mill. Mean viral mortalities for larvae fed red oak, red maple, pitch pine, and quaking aspen were 32.0, 35.4, 44.4, and 49.7%, respectively