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The effect of temperature on the rate of development of Xyleborus foicatus(Eichh.) was determined by rearing individuals under a range of constant temperatures (15- 32℃). Rates of development changed in a linear fashion over a wide range of temperatures.Estimates of lower development thresholds were obtained for eggs (15.7 ± 0.5℃), larvae(15.8 ± 0.8℃) and pupae (14.3 ± 1.4℃) and the degree days (DD) for development were 70 ± 4.4, 95 ± 8.5 and 72 ± 5.1 DD, respectively. Optimum temperature for development was around 30℃ for all stages. Temperature fluctuation in cooler High Country areas (above 1400 m) with a mean temperature around 15℃ seems to be critical for the development of the pest, which may be responsible for the near absence of pest in those areas. Temperature fluctuations (18- 30℃) in the Mid Country region (600- 1200 m) favor the development of the pest compared to development under constant conditions. The altitudinal distribution of the shot-hole borer across tea growing areas in Sri Lanka is, therefore, mainly goveed by temperature.