The volatile constituents of the supposed defensive secretions of the glandular pouches of the adults of both sexes of the cockroach Therea petiveriana have been shown to contain N-3-methylbutylacetamide (MBA) and N-3-methylbutylpropanamide (MBP), which represented 60% of the volatile fraction. The other 40% included acidic, aromatic, and aldehydic compounds. Behavioral experiments demonstrated that the secretion acts as an alarm pheromone for adults.