The study on occurrence regularity of Semiothisa cinerearia in Shenyang

Key Words：Semiothisa cinerearia, occurrence regularity, Shenyang, characteristics, law of field population fluctuation

Abstract：      The characteristics of each stage of Semiothisa cinerearia Bremer et Grey (adult, egg, larvae and pupae), and its behavior and habits, life history and population fluctuations, are described from laboratory and field observations in Shenyang. The results show that S. cinerearia has three non-overlapping generations a year and lives through the winter as pupae. The larvae undergo 7 instars. Instars 1-4 consume relatively little food but appetite increased markedly from the 5th instar after which larvae became extremely voracious with ingested food comprising 80%-90% of their body mass. Viability increased with each instar. The period of larval occurrence was from May to September and the most severe crop damage occurred in early and middle June and late July. Population size decreased after September when mature larvae begin to pupate and overwinter in soil.