SEASONAL BIOLOGY OF BIHAR HAIRY CATERPILLAR, SPILARCTIA OBLIQUA WALKER (LEPIDOPTERA: ARCTIIDAE) ON CASTOR, A PRIMARY FOOD PLANT OF ERI SILKWORM

The biological aspects of Bihar hairy caterpillar, Spilarctia obliqua Walker infesng castor, Ricinus corninunis (Non-bloomy red variety) were studied in different seasons at RSRS, Mendipathar. The biological parameters like larval period, pupal period, total life cycle, fecundity, hatchability, incubation period, and adult longevity were recorded during four seasons, viz. March- April, June-July, October-November and December-January. Egg incubation varied from 6.5 -10.5 days, the shortest in October-November and longest iii December-January. The season has no effect in the egg hatchability of the insect. The larval period varied from 24 days (June-July) to 44 days (December-January). Similarly, the total life cycle (egg to adult) took only 39.6 days in June- July and it was prolong up to 70 days during December-January. The fecundity was recorded maximum in October-November (987 eggs) and lowest in December-January. (654 eggs). Adult longevity was more or less same in all the seasons.