1 - Long-range insect migration in relation to climate and weather: Africa and Europe

Summary

Introduction

Although there are many records in the literature of individual insect migrations within Africa and Europe (see e.g. Williams, 1958; Johnson, 1969; Cayrol, 1972; Rainey, 1976; Pedgley, 1982; Dingle, 1985), there have been few attempts to review seasonal redistribution on a continental scale (but see Farrow (1990) for the migration of Acridoidea). Here we summarise the (now very extensive) available information on long-range, windborne movements by winged insects in the various climatic zones of Africa and Europe, and show how these migrations are related to the weather and to seasonal changes of climate and prevailing wind.

Some insect species migrate only short distances (a few hundred metres to a few kilometres) between habitat patches (see e.g. Solbreck, 1985), but we are concerned here with migration on scales covering countries and continents. These distances are so great, and the flying speeds of most insects are so slow (usually less than 3 m s⁻¹), that most migrations are dependent on the help of an external energy source: the wind. Persistent flight in a wind of, for example, 10 m s⁻¹ can easily result in migrations of 300-400 km in one day or night. In many (but by no means all) species, these migrations are made during the few days before the onset of breeding (Johnson, 1969; see also Chapter 10, this volume), and the movements are often dominated by a single weather system (Pedgley, 1982; Drake & Farrow, 1988).