Caloric reserves in salt marsh deer flies, Chrysops fuliginosus (Diptera: Tabanidae)

The behaviour of adults of Chrysops fuliginosus was observed near a salt marsh in Milford, Connecticut, during 1978, 1979 and 1982-83. Males and females were analysed by a chemical test to quantify available caloric reserves in mating, resting and blood-seeking individuals. Mean available energy reserves were highest in males (mean = 2.7 cal/mg) and females (mean = 2.5 cal/mg) captured in copula. There were no appreciable differences between these groups and males resting on vegetation (mean = 2.6 cal/mg), but lower amounts of mean available caloric reserves were noted for females resting on vegetation (mean = 1.2 cal/mg) or seeking vertebrate hosts (mean = 1.4 cal/mg). The relatively higher caloric values recorded for copulating C. fuliginosus and resting males were attributed to nectar-feeding and quantities of stored reserves remaining after eclosion.