The regression analysis of emergence was initially restricted to the models proposed earlier by Trematerra et al. (1996), but the 3-parameter sigmoid model (y ¼a/(1 þ exp((x b)/c)) provided better fits for cumulative emergence of populations of T. castaneum and O. surinamensis, as also observed by Fragoso et al. (2005), and the 3-parameter Gompertz model (y ¼a exp(exp((x b)/c)) provided better fits for populations of R. dominica. These models were therefore used.