In ants, division of labour is often associated with caste-specific adaptations. In this study, we examined the morphology of the venom apparatus (venom reservoir volume and sting length) and the composition and activity of the venom across castes (soldier, submajor and media/minor) of the army ant Eciton hamatum to investigate how caste differentiation influences venom traits. Morphometric analyses revealed that soldiers have larger venom reservoirs and longer stings, consistent with their spec