Dasheen horn worm, Theratra pinastrina MARTYN (Lepidoptera: Sphingidae) attacking dasheen leaves. 1. Seasonal prevalence

Abstract

Seasonal prevalence of the dasheen horn worm, Theratra pinastrina MARTYN, has been investigated by counting numbers of adults caught in a 20-w blacklight trap and by direct field observations at dasheen fields of Kushira district, Kagoshima Prefecture, in 1976-1978. The adults were caught in the trap during the period between mid-May and mid-October, more abundantly in August and September. The numbers of eggs and larvae in the field fluctuated in parallel with the number of adults caught in the trap. This species was considered to overwinter in the pupal stage, and there were four generations a year; the first generation lasted from mid-May to early July, the second from late June to early, August, the third from early August to mid-September, and the fourth from early September to mid-October. The male to female ratio was ca. 90 : 10 for the adults caught in the light trap.