A field study was conducted in 2005 to evaluate the effects of different levels of European corn borer (ECB), Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), feeding at three corn growth stages on whole-plant yield and forage quality. The experiment, which was conducted at the Virginia Tech Kentland Research Farm, consisted of a split-plot randomized complete block design that was replicated eight times. Each block consisted of three main plots, with each main plot representing one of the following plant growth stages: 10-leaf, 16-leaf, and blister. All main plots consisted of 6 subplots, with each subplot representing one of the following ECB infestation levels: 0, 1, 2, 3, 4, or 5 larvae per stalk. At the half kernel milkline stage, infested cornstalks were cut manually to record the number of tunnels per stalk. Four complete stalks, selected from each infestation level, were chopped into approximately 2.5 cm pieces and dried to determine percent dry matter and subsequent forage quality. ANOVA was performed to determine the effect of plant growth stage and ECB infestation level on whole-plant yield (dry matter). Fisher’s Protected LSD was used to determine differences among levels within significant main effects. ANOVA and Fisher’s Protected LSD also were performed to determine the effect of plant growth stage and ECB infestation level on acid detergent fiber (%), neutral detergent fiber (%), and crude protein (%) values.