A Field Study of Flight Temperatures in Moths in Relation to Body Weight and Wing Loading

Abstract

1. Flight temperatures were measured in representatives of ten families of moths-Sphingidae, Noctuidae, Geometridae, Arctiidae, Saturniidae, Ctenuchidae, Pericopidae, Lasiocampidae, Notodontidae and Pyralidae. 2. In all cases thoracic flight temperatures and abdominal flight temperatures were higher than ambient, and thoracic temperatures far exceeded abdominal temperatures. 3. Within the individual species, thoracic flight temperature was relatively uniform, and independent of ambient temperatures from 7 to 17°C. 4. Within the various families, flight temperature was independent of body weight except in the Ctenuchidae and Arctiidae; in these two closely related families, in contrast to all the others, body weight and wing loading were positively correlated. When the families are considered as units, mean thoracic flight temperature increased with mean body weight. 5. Between species in the same family and between families thoracic flight temperatures increased directly with wing loading. However, because thoracic flight temperature is affected by insulation and body weight, species with the same wing loading but belonging in different families may have markedly different flight temperatures. 6. Members of those families that have high flight temperatures and must undergo a pre-flight warm-up have attributes that reduce vulnerability to predation when at rest-threat display, death feigning, production of noxious secretions, and mimicry of stinging insects.