The developmental biology and adult longevity of Pezothrips kellyanus (Bagnall) (Thysanoptera: Thripidae) on lemon (Citrus limon L.) leaves was studied at five constant temperatures (15, 20, 25, 30, 32.5, and 357deg;C) under laboratory conditions. Developmental time and adult longevity were inversely related to temperature. The developmental time from egg to adult ranged from 10.1 d at 32.5°C to 40.3 d at 15°C. Adult thrips lived from 5.3 d at 35°C to 45.9 d at 15°C and females tended to live significantly longer than males at these two extreme temperatures. No significant differences were found in developmental times between male and female immature stages of P. kellyanus within each tested temperature regime. The highest larval to adult survival (80.6%) was found at 25°C and the lowest (50%) at 32.5°C. No larvae hatched from eggs incubated at 35°C. Both linear and nonlinear models adequately described the relationship between temperature and developmental rates for immature stages of P. kellyanus. Thus, thrips required 204.5 degree-days to complete development from egg to adult stage, above a minimum threshold of 10.2°C as estimated by linear regression. The temperature thresholds for all immature stages except for pupae of P. kellyanus, estimated by the linear model were similar to values that were estimated by the nonlinear model. The predicted upper lethal temperature was 33.12°C, with a minimum threshold for total development occurring at 10°C, as estimated by nonlinear model. The importance of the results in the management of this species through the prediction of its seasonal appearance and population levels are discussed.