Holometabolous insects are an extraordinarily species-rich animal taxon, characterized by a clear distinction between larvae, pupae and adults in their lifecycles. From a calorimetrist's point of view, they are interesting study objects because larvae and adults often have very different lifestyles. Some common patterns of the time course of metabolic rates are observed during calorimetric investigations. Larvae have high metabolic rates after hatching from the egg, up to 160 mW/g in the wax moth Galleria mellonella. Prior to pupation, metabolism is strongly reduced. During metamorphosis, the pupal instars typically exhibit a U-shaped pattern of heat production. Insect adults have low resting metabolic rates, close to the pupal metabolism. Metabolic rates of Eying insects are up to 50 times higher than resting metabolism.