Constant temperatures in the range 12.5 to 30°C allowed larval and pupal development inDacus oleae(Gmelin). Larval development ranged from 37.1 to 9.2 days, and pupal development from 48.6 to 9.3 days. The logistic equation was better than thermal summation at expressing larval, pupal and total (egg to adult, calculated) development. Thermal constant values were 186.3, 186.7, and 414.5 days-degrees respectively. The period from the beginning to the end of pupation due to individual variation ranged from 12 days (12.5°C) to six days (25, 27.5°C), to seven days (30°C). Respective values for adult emergence were six to ten days (12.5, 15°C), and two days (22.5°C). Percent pupation was highest at 25, 27.5°C, larval growth at 25, 27.5°C, and adult emergence at 22.5, 25°C, and lowest at 12.5°C, at 12.5 to 20°C, and 12.5°C respectively. At 12.5, and 30°C many adults did not emerge completely from the puparia (15.8%, 48% respectively). One-day exposure of pupae at 32.5°C and then transfer at 25°C was harmful during the first day of age but not later. Two-day exposure was even more harmful in the first two days than later. Exposure before adult emergence (9th day) affected emergence adversely, indicating that upper temperature threshold for emergence is lower than that for development.Temperature effect on development is discussed within the context of rearingD. oleaein the laboratory.