Energetics and Thermoregulation of Malacosoma Americanum (Lepidoptera: Lasiocampidae) during Hovering Flight

Abstract

Oxygen consumption of the eastern tent caterpillar moth, Malacosoma americanum (mean body mass = 88 mg), during free hovering flight was independent of ambient temperature from 17 to 30 C and averaged 126 ml of O₂ (g · h)⁻¹. Mean wing stroke frequency was also unaffected by Ta and varied between 56 and 58 (s⁻¹). Thoracic temperature varied between 34 and 41 C between Ta's of 10-30 C. Thoracic conductance of intact (dead) moths in still air is similar to predicted values and increased by 75% between air flows of 0 and 2.0 m · s⁻¹. Thoracic insulation significantly retarded thoracic cooling and this effect was more pronounced at high than at low wind speeds. High levels of heat production compared with other moths of similar mass are a consequence of higher power requirements resulting from relatively small wings operating at high stroke frequencies. High Tth is necessary for the initiation of flight. During flight at moderate and high Ta, heat loss is regulated to prevent thoracic overheating.