Eri silkworm (Samia Cynthia ricini Boisduval) cocoon weight is varied from <1.5 g to >2.5 g. According to sizes of cocoon harvested from nine locations were graded into four categories viz., grade I- >2.5 g, grade II- 2-2.5 g, grade III-1.5 g-2.0, grade IV-mixture of all to study the grainage performance. Correlation studies between cocoon weight on the one hand and adult emergence, copulation potential, fecundity, eggs per gram and egg hatchability on the other separately revealed that the cocoon weight had significant positive correlation with fecundity and egg hatchability and negative correlation to eggs per gram. Egg hatchability was greater in the batches of Kollihills compared to other locations. Grainage experiment was conducted in three different months (Sep, Oct, and Dec 2004) on the cocoons harvested from seven locations. Among these selected cocoons kollihills, Coimbatore and kullappanaickanur batches were showed better performance in all grainage parameters and cocoon weights ranged from 2 to 2.5 g is ideal for better grainage parameters. The impact of different matting period revealed that the potential copulation period is 5 hrs. In an experiment, using ten oviposition devices for eri silkmoth, the highest egg laying was observed in jackfruit kharika (369.4) and others were statistically not different. Among the all devices tried, the nylon net bag has more advantageous due to the following parameters like keeping moth individually, harvesting of eggs, disinfection and saving the time and labour considerably.