Derivation of growth exponent from growth rate on day 3. (a) The relationship between growth rate and growth exponent for larvae with the same initial weight. The relationship is best fit by a logarithmic regression where k = 0.2*ln(GR) + C, where C is a constant that depends on the initial weight of the instar. In this regression the initial weight was 1.5 g, which gives C = 0.25. (b) The relationship between C and the initial weight. An exponential regression gives the best fit. Substituting the equation in (b) for the constant C in k = 0.2*ln(GR) + C gives k = 0.2*ln(GR) + . So k can be deduced from the initial weight of the instar and the growth rate on the third day of the instar.