none. Using gravimetric and calorimetric measurements, we have studied the action of thermal environmental variations (from a 25-15°C thermoperiod to 30-20°C) on the total energy spent during the endoparasitic development of Diadromus pulchellus and D. collaris (Hymenoptera: Ichneumonidae) in the pupae of Acrolepiopsis assectella Z. (Hymenoptera: Plutellidae) to maintain their basal metabolism, activity and thermoregulation. These two Diadromus species expended an identical 24 h maintenance energy in the 25-15°C thermoperiod (0.24 cal/24 h for females and 0.26 cal/24 h for males). Maintenance energy in the 30-20°C thermoperiod was identical in males (0.38 cal/24 h) and somewhat different in females (0.35 and 0.37 cal/24 h respectively). A 5°C temperature increase (15 to 20°C and 25 to 30°C) during the dark and light periods resulted in increased 24 h energy expenditures by both species, somewhat greater in D. pulchellus females.