Introduction

The previous chapters of this volume review and provide a contemporary synthesis of current knowledge about several of the world's most significant insect migration systems, and of the adaptations that enable these systems to function and persist. They illustrate the wealth of information that has been accumulated, and the understanding that has been developed, during the last two to three decades: the period since the ‘turning point in the study of insect migration’ declared by Kennedy (1961), Southwood's (1962) association of migration with temporary habitats, the publication of the comprehensive review by Johnson (1969), and the development of ‘entomological’ radars by Schaefer (1976).

Along with previous general (e.g. Johnson, 1969; Dingle, 1980,1984; Kennedy, 1985) and more specific (e.g. Drake & Farrow, 1988; Gatehouse, 1989; Farrow, 1990) reviews, the foregoing chapters clearly indicate that migration is a common and widespread phenomenon, both geographically and across taxa. They also show that, while the details may vary from species to species and between geographical or climatic regions, many features of insect migration are common to most species and localities. The recognition (often gradual and implicit) of these more general features over the last decade or so has provided a series of insights that together amount to a major conceptual advance. Among the most important of these insights are:

1. Migration is actively initiated, maintained and terminated; it is not a ‘passive’ process or in any sense ‘accidental’ (Kennedy, 1961).

2. […]