LABORATORY STUDIES ON THE LIFE-CYCLE AND GROWTH OF CLOEON SP (EPHEMEROPTERA, BAETIDAE) IN MEGHALAYA STATE, INDIA

The number of nymphal instars in the life cycle of Cloeon sp. was found to vary from 10-14, though more than 50 percent of the nymphs emerged as subimagines in the tenth instar. The size range of different instars overlapped considerably. This could possibly be attributed either to a differential growth rate among nymphs or to sexual dimorphism or both. The species was found to be a multivoltine one with numerous overlapping generations in summer. However, growth slowed down in winter and the nymphs took a longer time to complete their life cycle. Temperature was found to be the most significant factor influencing growth under laboratory conditions.