Correlation of sound generation and metabolic heat flux in the bumblebee Bombus lapidarius

Abstract
Flying insects produce extreme amounts of heat as a by-product during the contractions of their thoracic flight muscles (Heinrich, 1989). Before flight, metabolic heat may serve to warm up the thoracic muscles until the minimum lift-off temperature is reached (Heinrich, 1974b; Stone and Willmer, 1989; Esch and Goller, 1991). Social bees and wasps are also able to use the heat produced in their flight muscles for brood incubation and for active regulation of nest temperatures (Heinrich, 1974a; Seeley and Heinrich, 1981; Schultze-Motel, 1991).