Evidence of autumn overseas migration in the rice planthoppers, Nilaparvata lugens and Sogatella furcifera: analysis of light trap catches and associated weather patterns

ABSTRACT. 1. Daily trap catches of the rice planthoppers, N.lugens Stal and S.furcifera Horvath, and associated synoptic weather patterns were analysed in Kyushu, south‐west Japan, in the autumns of 1980–85. 2. Certain weather patterns which seemed to favour overseas immigration, were reflected in trap catches: of eighteen occasions in which back‐tracks on 850 mbar wind fields reached central China, marked mass catches in a light trap occurred on six occasions, and peaks in catch curves were found on another seven occasions. 3. These results strongly imply overseas immigration of the planthoppers from China to Kyushu in autumn, identical to invasions by the same species in early summer. However, such autumn migration is apparently non‐adaptive because migrants or their progeny are soon killed by cold weather.