Aposematic traits such as bright contrasting coloration and gregarious feeding are often signals to predators that a potential prey is unpalatable. Larvae of Ceratomia catalpae (Boisduval) (Lepidoptera: Sphingidae), the catalpa sphinx, show aposematic traits and sequester catalpol, a secondary compound from their host plant Catalpa spp. (Bignoniaceae). Catalpol sequestration by other caterpillar species has been shown to deter both invertebrate and vertebrate predators, but the palatability of C. catalpae has not been explicitly tested. Choice tests were performed with spiders (Hogna carolinensis Walckenaer, Araneae: Lycosidae) and predatory hemipterans (Podisus maculiventris [Say], Hemiptera: Pentatomidae). These tests showed that predators naïve to both C. catalpae and the alternate prey Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae) and Manduca sexta (L.) (Lepidoptera: Sphingidae) preferred the alternate species, and that P. maculiventris that were exposed previously to T. ni also preferred T. ni. In nonchoice tests, P. maculiventris grew significantly more slowly upon C. catalpae compared to M. sexta. These results suggest that C. catalpae, like other caterpillars that sequester catalpol, is less palatable to invertebrate predators compared to nonsequestering caterpillar species.