1. Moths ‘warm-up’ prior to flight at mean rates of 4.06° C./min. in Celerio lineata and 2.5° C./min. in Rothschildia jacobae. The abdominal temperature rises only 2-3° C. during activity.

2. Oxygen consumption of torpid sphinx moths increases by a factor of 2.27 as temperature changes from 26° to 36° C.

3. Oxygen consumption during ‘warm-up’ increases with duration of ‘warm-up’ from about 1000 µl./g. min during the initial 30 sec. to nearly 1600µl./g. min. during the 3rd min. This increase compensates for increasing heat loss from the thorax during ‘warm-up‘.

4. When the moths are regulating thoracic temperature, oxygen consumption increases with decreasing air temperature from a mean of about 400µl./g. min at 31° C. to about 650µl./g. min. at 26° C

5. Values of O2 consumption calculated from the cooling curve of C. lineata are about 85% of the measured values of O2 consumption.

6. The giant silk moth, Rothschildia jacobae, regulates thoracic temperature during activity between about 32° and 36° C. at ambient temperature from 17° to 29° C. Moths kept at high temperatures are active longer, have more periods of activity and expend more energy for thermoregulation than moths kept at low temperatures.

7. Large moths increase metabolism during active periods to offset heat loss and thereby maintain a relatively constant internal temperature. In this regard they may be considered endothermic, like birds and mammals.

8. We estimate that male moths use 10% of their stored fat for thermoregulation, while females may use 50%.

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