The nutritional quality of host plant is critically important for insect herbivores to maximize their fitness, but it is relatively unexplored whether the ingestion of a specific host plant will have the same effects on insects under different thermal conditions. We have used a multi-factorial experimental design to investigate how the nutritional quality of host plant and temperature interact to affect life-history traits in a generalist caterpillar Hyphantria cunea (Lepidoptera: Arctiidae) feeding on five different host plants. Caterpillars raised on Platanus occidentalis, Sophora japonica and Prunus x yedoensis exhibited substantially higher survival, faster growth and heavier mass at pupation than those on Cornus kousa and Betula platyphylla. Caterpillars developed more quickly and attained a smaller final body mass at higher temperatures, but the way that these traits responded to temperature differed by host plant. Caterpillars on P.occidentalis displayed a monotonic decrease in development time with increasing temperature, but the development time of those on P. x yedoensis declined with temperature in a biphasic manner. Furthermore, the rate at which pupal mass increased with decreasing temperature was much greater for caterpillars on P.occidentalis than those on P. x yedoensis.