We proposed two improvements to the Logan model of temperature-dependent development. We first eliminated a redundant parameter (modification 1) then incorporated an intercept parameter (modification2), thereby resolving the inability of the original model to estimate a low-temperature developmental threshold. The three model versions were compared using temperature-dependent developmental rates in six insect species (a total of 11 life stages).The original model and modification 1 produced identical curves. In 10 of the 11 cases, modification2 had the highest r2and the least estimation bias.