Social insects offer exciting prospects for ageing research due to the striking differences in lifespan among castes, with queens living up to an order of magnitude longer than workers. A popular theory is that senescence is primarily the result of an accumulation of somatic damage with age, balanced by investment into processes of somatic maintenance. Investigation of these predictions in social insects has produced mixed results: neither damage accumulation nor investment into somatic maintenance is consistently different between castes with different lifespans. We discuss some limitations of the studies conducted thus far and consider an alternative proximate theory of ageing that has been recently proposed.