Chrysomya megacephala (F.) and Chrysomya putoria (Wiedemann) (Diptera: Calliphoridae) are considered of forensic, medical, and veterinary importance in Brazil because of their necrophagous and synanthropic behaviour. The development of flies can be influenced by temperature, and species from the same genus usually have different responses to external variables. The egg development of blow fly can be a useful complementary technique to estimate the minimum postmortem interval. Thus, this study aimed to compare the egg developmental time and survival of C. megacephala and C. putoria at different temperatures to determine the optimal temperature for egg development and the linear regression for developmental time and temperature, thereby determining the minimum threshold (t) and thermal summation constant (K) for each species. Adults of both species were collected in the region of Campinas city, São Paulo state, Brazil. Eggs were incubated at eight constant temperatures between 05 ± 1°C and 35 ± 1°C and the egg developmental time and survival were evaluated. There was no egg survival at 5 and 10°C. The K for C. megacephala and C. putoria were 179.41 HD and 189.94 HD, respectively. The regression slopes and t (10°C) were similar for both species. The optimal temperature for egg survival was between 25 and 35°C, for C. megacephala and 20 and 30°C, for C. putoria. The present data were similar to most data available in the literature, but differences in the same species are a possibility.