Ecology and methods of control of the rice water weevil, Lissorhoptrus oryzophilus KUSCHEL in Kagoshima Prefecture. 3. Activity of adults in early planted paddy fields.

Behavior of adults of L. oryzophilus and their migration from overwintering sites to early planted paddy fields and vice versa was observed from 1985 to 1987 in Kagoshima Prefecture, and the following ecological characteristics of the weevil were noted. Adults derived from the larvae which developed in early planted paddy fields appeared from mid-June to July, feeding on ineffective tillers and other gramineous weeds which grew on ridges. In July they flew to waste lands of Imperata cvlindrica, hedges and elsewhere around the paddy fields, where they buried into soil, and overwintered until the following February. Overwintered adults appeared from early to mid-March, feeding on new leaves of I. cylindrica. The number of adults reached a peak in early April. Thereafter they flew to early planted paddy fields from the overwintering sites from mid-April to early May soon after the start of transplanting.