Migration

Most species of Auchenorrhyncha are relatively sedentary, completing their life cycle within a small area. Although most species have well-developed wings and are strong fliers, few seem to move more than a kilometer from their birthplace. Many species, particularly those inhabiting grasslands and deserts, are submacropterous or brachypterous [short winged, Fig. 3(10)] and, thus, incapable of sustained flight. Some of these species occasionally produce macropterous (long-winged) females that move to new patches of suitable habitat. Other species produce both short- and long-winged forms either simultaneously or in alternate generations. The proportion of macropterous to brachypterous forms often varies in response to population density. Some Auchenor-rhyncha species undergo annual migrations that may cover hundreds of kilometers. Not coincidentally, many of these accomplished migrants are important agricultural pests. Among the best studied of these are the brown planthopper (Nilaparvata lugens) and the potato leafhopper (Empoasca fabae). Neither of these species can normally overwinter in high latitudes. Populations build up in the tropical or subtropical parts of their range and migrate to higher latitudes each spring. They are assisted in their migratory flights by convection and favorable winds, and the initiation of migratory behavior is apparently triggered by favorable atmospheric conditions. Sporadic incidents of very-long-range migrations have also been documented. In one such incident in 1976, swarms of Balclutha pauxilla (Cicadellidae), probably originating from a source population in Angola, descended on Ascension Island, 2700 km away in the mid-Atlantic.

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