The duration of development ofCatolaccus grandis(Burks) (parasitoid of the cotton boll weevil,Anthonomus grandisBoheman) was detennined at seven constant temperatures. Nonlinear regression analysis was used to test the fit of temperature-dependent developmental rates to the poikilotherm and Logan models. The mean total developmental time ofC. grandiswas significantly shorter in males than in females. The females completed development in 38.2, 22.5, 18.7, 15.0, 13.3, and 11.8 d from egg to emergence at 18, 21, 24, 27, 30, and 33°C. Development in males required 32.2, 18.0, 15.3, 13.0, 11.8, and 11.1 d from egg to adult at the same respective temperatures. All individuals were unable to complete development at 36°C, but they developed successfully to the fifth instar at this temperature. No evidence of development was observed at 39°C. The three models tested fitted the data similarly well; however, the Logan 1 model is recommended over Logan 2 because of its simplicity. Developmental rates of the boll weevil and the native parasitoidBracon mellitorSay are compared with those observed onC. grandis. Implications on the adaptability ofC. grandisto the South Texas environment are discussed.