USDA-ARS Insect Chemical Ecology Laboratory, Agricultural Research Center-West, B-007, rm301, Beltsville, 20705 Maryland, USA.
Both males and females of the aposematic butterfly Agraulis vanillae produce an abdominal secretion when stimulated. This discharge contains a mixture of natural products which includes monoterpenes and distinctive esters. The failure of birds belonging to a large variety of species to feed on A. vanillae may be correlated with the presence of the abdominal defensive allomones.