GC-MS analysis of the defensive secretion from the millipede Buzonium crassipes showed three volatile components, beta-pinene (35%), limonene (6%) and a new alkaloid, buzonamine (59%). Buzonamine had an HRMS molecular ion at m/z = 221.1785 (calculated for C14H23NO, 221.1781), 14 carbons in the C-13-NMR and 23 hydrogens by SFORD, DEFT and APT experiments. All distinct H-1 nuclei were assigned to C-13 resonances with 2D H-1-C-13 COSY data, and the final structure was determined by H-1-H-1 COSY, H-1-C-13 HMBC and nOe experiments, Buzonamine contains four rings including an epoxy group and a tertiary nitrogen. P-Pinene, limonene or buzonamine, kept the mound nesting ant, Formica obscuripes, from eating mealworms (Tenebrio molitor) treated with 1 mg of the chemical. A 150 mg millipede expels 4 mg of secretion. (C) 2000 Elsevier Science Ltd. All rights reserved.