This research studied the effect of temperature on the reproduction of Bracon vulgaris Ashmead (Hymenoptera: Braconidae), an ectoparasitoid of the cotton boll weevil Anthonomus grandis Boheman (Coleoptera: Curculionidae), in climatic chambers, using constant temperatures of 20, 25, and 30°C, relative air humidity of 70 ± 10% and a photophase of 14 h. Females of the parasitoid produced a greater number of eggs when exposed to 25°C (124.65 eggs) in relation to those exposed to 20 (43.40 eggs) and 30°C (49.60 eggs). The mean number of parasitized larvae per female of B. vulgaris at 25°C (71.75) was greater than at 20°C (31.40) and 30°C (25.15). The daily intrinsic rates of increase (r_m) were -0.007 at 20°C, 0.07 at 25°C and 0.03 at 30°C, revealing that the temperature of 25°C produced increases of 1,100 and 133% in the value r_m in relation to the temperatures of 20 and 30°C, respectively. In programs of biological control of the boll weevil using innoculative releases, adult females of B. vulgaris with approximately five (at 25 or 30°C) or 20 day old (at 20°C) should be used; when using innundative releases, adult females of B. vulgaris, with ages between 11 and 31; 9 and 29 or 3 and 14 days of age, respectively, at 20, 25, or 30°C should be used.