The effect of temperature on rate of development and survival of the immature stages of a subtropical population of the black jezebel, Delias nigrina, was studied under laboratory conditions at a range of constant temperatures. Mean developmental times from first-instar larva to adult varied from 29 days at 27àto 52 days at 19û the development threshold temperature and thermal constant were estimated to be 9àand 494 degree-days, respectively. Larval developmental rates reached physiological maximum at the higher temperatures tested (25-27é. Pupal development, by contrast, was not affected in the same way as larvae by higher temperature. Survival of the immature stages varied inversely with temperature: survival was highest at 19àand significantly reduced at 27î Mortality at the higher temperature was attributable mainly to final-instar larvae and pupae. These findings indicate that, compared with other tropical pierids that have been studied, D. nigrina has: (i) a comparatively low temperature threshold; (ii) a slow rate of development; and (iii) a poor tolerance to moderately high temperatures. Physiologically, these features are more characteristic of a temperate butterfly than a tropical one. This physiological response appears to be reflected by the temperate nature of the genus as a whole, which may be related to its period of origin and evolution during past climatic events.