Defensive Secretion of a Caterpillar (Papilio)

Science  24 Dec 1965:
Vol. 150, Issue 3704, pp. 1733-1735
DOI: 10.1126/science.150.3704.1733


The eversible cervical gland (osmeterium) of the caterpillar of the swallowtail butterfly, Papilio machaon, produces a secretion containing isobutyric and 2-methylbutyric acid. The gland is effective in defense against ants. Even when caterpillars were fed on one of three unbelliferous plants (fennel, carrot, parsnip) the secretion contained the same two acids.