Bioenergetica, efficiencies of energy transfer and growth of Spodoptera litura larvae reared on mulberry, cabbage, castor and wild hempweed leaves were determined using calorimetrie procedures. Energy contents (J mg−1 ash-free tissue) of castor leaves were higher than those of cabbage, mulberry and wild hempweed. Fresh leaves had slightly higher energy contents than those left over. The rates of ingestion and egestion of food energy increased linearly with the age of larvae. Energy consumption decreased exponentially with larval age, and this decreasing trend showed an intermediate rise at the fifth instar. Assimilation efficiencies were highest and lowest for the first and sixth instar larvae respectively. Efficiencies of gross and net larval production showed linear increases with instar stage, except at the fifth instar which showed dramatic declines in conversion of ingested and assimilated energy into insect biomass. Efficiencies of gross and net productions during early first to third instars were low, but those during the sixth instar were high. The pathways of energy transfer indicated that an average of 58.5% of the total energy ingested was lost directly through faeces, respiration and exuviae, while about 42.2% of the total energy ingested was actually converted into growth of an S. litura larva.