Subcoccinella vigintiquatuorpunctata, an herbivorous coccinellid beetle of Eurasian origin, is now established in New England, as evidenced by the persistence of two central Connecticut populations from 1997–2001. The beetle's pupal surface bears glandular hairs that produce a secretion known to consist principally of three polyazamacrolide alkaloids. We demonstrate that the secretion serves as a potent antipredator defense: contact with it elicited pronounced cleaning activity by the predatory ant Crematogaster lineolata. Additionally, application of the secretion to palatable food items rendered them unacceptable to the ant. This is one of few studies to examine the chemical defense of an introduced animal vis à vis a predator native to its new environment.