It appears that retirement is not present only in human communities.
Leaf-cutter ants start their lives with razor-like jaws, or mandibles, to cut through the leaves they harvest. But as these "wear out", the insects tend to carry the leaves cut by their younger counterparts.
Read more: http://news.bbc.co.uk/earth/hi/earth_news/newsid_9306000/9306830.stm