Scampering across the salt pans of Tunisia on their spindly legs, desert ants (Cataglyphis fortis) have a single-minded mission: locate food and get it back to the nest. Normally, individual raiders bear a tasty morsel in their mandibles and navigate home along the most direct return route, regardless of how tortuous the outbound journey was. However, their determination is often tested to the extreme when the robust animals stumble upon a particularly large piece of food - such as a dead spider or locust. Undaunted, the scavenger simply drags the feast backwards: 'They are really awesome', chuckles Matthias Wittlinger from the University of Ulm, Germany. However, how do the insects navigate while reversing? 'All the cues are from the other direction', says Wittlinger.