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The carpenter bee Xylocopa capituta has a high wing loading (425 mg cm-2 in females with empty crops) and exhibits a very high mass-specific oxygen consumption during flight (mean for free flight 52.3 ml O3 gm-' hour').Evaporative water loss is also high during flight (26.6 mg gm-I hour') and is significantly correlated with rate of oxygen consumption (r = 0.73) as well as with temperature of the ambient air (r = 0.80) and the water vapor deficit (r = 0.66). No indication of active evaporative cooling was evident and the bees are true endotherms capable of rapid preflight thermogenesis. Analysis of the osmotic and ionic concentrations of the body fluids showed that no water stress was experienced by the bees.The use of suitable thermocouples and a sensitive capacitance-type humidity meter in an open flow-through system allowed instantaneous and simultaneous measurement of oxygen consumption, evaporative water loss, and thoracic temperature. All three variables fluctuated in close synchrony during preflight warmup, flight, and subsequent cooling.

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At 22°C the resting oxygen consumption of G. capensis is 1.13±0.05 cmO·g·h (mean± S.E.). In loose sandy soil the burrowing metabolic rate was approximately three times that of resting (3.41±0.19 cmO·g· h). Rate of oxygen consumption while burrowing bears a linear relationship with rate of burrowing. The equation of the regression line describing this relationship was used to construct a model for calculating energy expenditure of burrowing in free-living mole-rats. The diet of G. capensis consists of some green plant material and geophyte corms. The latter has a mean gross energy content of 16.36 kJ·g dry weight. The digestibility coefficient for captive G. capensis fed on sweet potato, was 97.42±0.41%. Data collected from an excavated burrow system revealed that the total energetic cost of constructing the burrow amounted to 79% of the estimated digestible energy available from geophyte corms in the area. A food store in the same burrow system was sufficient to meet the maintenance requirements of an adult G. capensis, resting at 22°C, for approximately 80-85 days. Soil samples taken at random adjacent to the burrow contained corms with a mean estimated digestible energy value of 2084 kJ per m of soil. A comparison of energetic cost of burrowing and randomly available digestible energy in the field suggests that foraging patterns are not random.