Sunn Pest, Eurygaster integriceps is a serious insect pest of wheat and barley throughout West and Central Asia. Effects of temperature on the development and survival of different stages of E. integriceps were studied. The thermal requirements for each stage were determined separately to provide the basis of a phenology model designed to improve chemical control. The standard linear regression method and the Ikemoto and Takai method of insect development were compared for the goodness of fit to the different stage development of Sunn Pest at constant temperatures to determine a developmental lower threshold (T0) and degree day (DD) requirements for each stage separately. Of the two methods, the Ikemoto and Takai method had the better fit and lowest standard error for the parameters of interest. Thus, the Ikemoto and Takai model was chosen to estimate the critical parameters, lower temperature threshold (T0), and thermal constant for different stages of development of Sunn pest. The estimated low-threshold temperature by Ikemoto and Takai method for egg, NI, NII, NIII, NIV, and NV were 16.226, 14.761, 16.645, 20.675, 21.489 and 19.229 °C respectively. The thermal constants were 51.224, 34.279, 61.017, 33.365, 34.477 and 69.981 DD (Degree-day), respectively). Results are useful for predicting the population dynamics of E. integriceps and thus provide information on this important insect pest that may assist in its management.