Thermoregulation by Winter-Flying Endothermic Moths

Noctuid moths of the subfamily Cuculiinae fly in any month of the winter in the north-eastern United States when air temperatures are at least 0°C. At lower temperatures they hide under leaf litter rather than perching on trees like many summer-flying noctuid moths. Like moths of similar mass and wing-loading that fly in the summer or that reside in tropical regions, the nocturnal cuculinids fly with a thoracic temperature of 30–35°C. The generation and maintenance of such high thoracic temperatures at low air temperatures depends on (1) the ability to begin shivering at very low muscle temperatures, (2) a thick insulating pile, and (3) counter-current heat exchangers that retard heat flow to the head and to the abdomen, respectively.