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 rubraL., or red maple,Acer rubrumL., showed significantly lower mean mortality due to the virus than did larvae fed virus on quaking aspen,Populus tremuloidesMichx., or pitch pine,Pinus rigidaMill. 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.