development of the tomato bug Nesidiocoris (Cyrtopeltis) tenuis (Reuter) (Heteroptera: Miridae) was studied at constant temperatures (15, 20, 25 and 30 ̊C ±1 ̊C). Development of immature stages was accelerated by raising of tested temperatures. Total averaged of developmental period was (76.13, 45.27, 26.73 and 20.93 days) at 15, 20, 25 and 30 ̊C; respectively. Generation period ranged between 93.50 and 22.80 days depending on rearing temperature. Addionally, adult female survived slightly longer than male; also, fecundity was higher at lower temperature (15 ̊C) than higher one (30 ̊C). Thermal constant or threshold of development (to), Thermal requirements (K) and degree- days (d. d. 's) were estimated to be 12.4, 7.8 and 9.9 ̊C for egg, nymph and all immature stages, respectively. Based on 30 ̊C estimation (preferred temperature), 107.83, 325.46 and 417.30 heat units (U.T.) are required for completion the development of egg, nymph and all immature stages. Development of one generation may require 440.29 degree-days.