The sensory and neuronal mechanisms underlying long-distance migration in insects

Many animals, such as birds and bats, are capable of migrating over vast distances to specific destinations. Remarkably, even insects such as the North American Monarch butterfly and the Australian Bogong moth undertake similarly long-distance migrations to specific sites. Here, we provide an overview of our current understanding of the migration of these insects and outline the sensory cues and neural mechanisms that underpin their journeys. We propose that their migrations can be divided into two phases: a "global" phase relying on global compass cues for long-distance navigation towards the goal, and a "local" phase where local sensory cues trigger innate recognition of features near and at the goal. The relevance of each phase depends on the insect's distance from its destination and is characterised by a specific relative weighting of sensory cues. We further propose a neural substrate for migration that supports robust decision-making about when to transition between phases, enabling migrants to navigate to their destinations with high efficiency.