Authors studied the temperature influence in the life cycle of Triatoma melanosoma Martínez, Olmedo & Carcavallo, 1987. Two study groups were used, one was maintained at temperatures of 28 ± 1oC and 80 ± 5% RH, with a photophase of 12 hr, the other was kept at environmental temperature, daily recorded, and a RH varying from 70 to 90%. After hatching, insects were fed once a week on pigeons. Results were analyzed with the Mann-Whitney test, showing that a mean increase of 2oC was suficient for a significant acceleration of the embryonic development. Comparing nymphal stages of both groups, no significant differences were found, except in the second instar nymphs.