Energetics, growth and development of workers and drones of the European honeybee Apis mellifera carnica were determined by classical isoperibol Calvet calorimetry and by combustion bomb calorimetry during one breeding season. Development was followed from the moment of egg laying till to the hatching of young adults. Mass, heat production rate and specific heat production rate served as experimental parameters registered daily. Two worker and two drone larvae remained after capping for 2 weeks in the calorimeter to continuously monitor their metabolism, their locomotor activity, moulting and hatching. Drone mass and metabolism were significantly higher than those of workers in all states of development. The energy content during the development of workers and drones was evaluated by combustion calorimetry and by CHN analyses combined with the Dulong equation or derivatives of it. (C) 2005 Elsevier B.V. All rights reserved.