none Cotesia diurnii Rao & Nikam, a larval parasitoid of Exelastis atomosa Wals. was studied under laboratory conditions (24 +- 1 degree C, 55-60% R.H.). The egges are white and hymeyopteriform. Eclosion occurs 3 days after oviposition. There are 3 instars, the first two are vesiculate and last hymenopteriform. Matured parasitoid larvae emerged from the host, killing it and then spun a silver-white cylindrical cocoon. Total developmental time from egg to adult was about 18 days: egg stage 3 days, larval stage 10 days and pupal stages 5 days.