Riders on the wind: The aeroecology of insect migrants

Migratory flight close to the Earth's surface (within the so-called flight boundary layer) occurs in some insects, but the vast majority of migrants ascend above this layer and harness the power of the wind for transport. The resulting displacements range from dispersive movements over a few tens of metres to seasonal migrations covering thousands of kilometres. In this chapter, we summarize knowledge of the use of the aerosphere by insects, focusing particularly on longer migrations, in relation to: the height and duration of flight, direction and speed of movement, seasonal and diel patterns, and responses to atmospheric conditions and phenomena. The seasonal mass movements have major ecological consequences in the invaded areas, and these are discussed briefly. We also highlight recent comparisons of insect movement strategies with those of flying vertebrates and mention interactions between these groups in the atmosphere. We conclude with some suggestions for the future development of these topics.