A comparison of the weeds Sida acuta Burm. f. and S. rhombifolia L. (Malvaceae) as hosts to the potential biological control agent Calligrapha pantherina Stal (Coleoptera: Chrysomelidae) was made in laboratory and glasshouse trials to assess whether host nutritional factors can explain the observed differential performance on these two hosts in the field. There were only minor differences in the life history parameters of insects reared on the two hosts. Larval development time was significantly longer and pupal weights were significantly lower on S. acuta. Survivorship, generation time, net reproductive rate, and the intrinsic rate of increase were not significantly different between hosts. Nutritional indices measuring utilization of the hosts by the insect were also not significantly different between hosts. On the basis of host nutritional factors both species are comparable hosts for C. pantherina. Matching the climate of the native range of this insect to Australia indicates that climatic factors may explain the observed distribution of establishment.