The energy budget of xylem-feeding Corymbia rubra (Coleoptera: Cerambycidae) larvae was estimated by determining bioenergetic parameters. The values of several of the life history and bioenergetic parameters of this wood-feeding insect are exceptional and associated with specific adaptations to living in and feeding on wood. The energy budget of C. rubra sheds light on the life strategy of a xylem-feeder. Its slow growth (0.012 mg × mg-1 × d-1) is associated with a low consumption rate (0.097 mg × mg-1 × d-1) and the low nutritional value of its food (the assimilation efficiency is 34%). The gross growth and net growth efficiency are 15% and 43%, respectively.