The Schaus swallowtail butterfly, Heraclides aristodemus ponceanus, is an endangered species of butterfly in Florida with critically low numbers. Habitat loss is an important component in its decline, but exotic species are having a detrimental effect. .
Clayborn and Koptur* excluded ants from interacting with the caterpillars and found decreased survival when ants are not excluded. The most problematic species was Pseudomyrmex gracilis the Elongate twig ant, an exotic species from Mexico and not native to Florida. These ant predators were the most aggressive toward Schaus Swallowtail caterpillars of any of the ant species observed. The threat to endangered butterflies is one more reason to guard against transport of exotic species.
*Jaeson Clayborn & Suzanne Koptur. 2017. Mortal combat between ants and caterpillars: an ominous threat to the endangered Schaus swallowtail butterfly in the Florida Keys, USA. Journal of Insect Conservation. pp 1–14. First Online: 14 July 2017