I investigated the effect of environmental factors (temperature and food availability) on the development and growth of semiaquatic bug Microvelia reticulata Burmeister, 1835. I focused on the developmental rate isomorphy. In a cross-designed experiment, M. reticulata was individually kept over whole juvenile period (eggs to reaching maturity) and subjected to treatments of three temperature (17, 21, 25 °C) and two food availability (full - daily feeding and reduced - 2 days interval) and their interaction. Development and growth was strongly influenced by temperature. Longest postembryonic development measured in individuals kept in the lowest temperature (54 days) contrasted to those kept in the highest temperature (16 days). Mortality was also significantly influenced by temperature; highest mortality rate was found in the 17 °C treatment. Effect of food availability was significant only in low temperature, resulting in the better survival of individuals on the high food level. In other temperature treatments, I found no effect of food on survival rate of M. reticulata. However, the food level influenced development significantly. In the 21 °C and 25 °C treatment, individuals on a full food developed faster than individuals on a reduced food. In 17 °C the food availability had no effect on time required to reach maturity. The best fitness (expressed as combination of low mortality rate and short development) was observed in 21 °C, both other temperature treatment were found stressing. Food availability had stronger effect on female individuals compared to males. In conclusion, I found no evidence of developmental rate isomorphy in M. reticulata. The research was supported by project of the Grant Agency of the Czech Republic GAČR P505/10/0096.