The logarithmic growth curve of 3 larvae and log weight of excrements were linear till 200 mg larval weight (1000 times weight increase). At 300 mg larval growth ceased after 9 moults, but eating continued. After cooling one pupated and the others went on eating without gaining weight. Monthly samples of a larger population gave a similar growth curve. Larval dry weight and fat content changed rapidly when growth decelerated logarithmically. Within age groups larval weight was normally strictly proportional to consumption. Difference between logs of larval weight and consumption decreased extremely slowly during growth, but rapidly after 200 mg. Within age groups larger larvae had higher economy of growth. Excrements were proportional to consumption, and digestibility was analysed as log differences. The general exponential character of insect growth is reviewed. Log transformation is relevant because deviations are described clearly: initial acceleration, effect of ecdyses, cessation of growth, and fluctuations in growth rate caused by environment. Log transformation stabilizes the variance and gives normal distribution during whole life.