Laboratory studies were conducted on the host range and host age preference by Eucelatoria bryani Sabrosky, a promising parasitoid of cotton bollworm, Helicoverpa spp. Among ten species of lepidopterous larvae of fourth instar exposed for parasitisation, only Helicoverpa armigera (Hubncr) was accepted by the parasitoid. The parasitoid preferred fourth and fifth instar larvae of //. armigera in which percentage of parasitisation and number of puparia recovered per host larva was 100 and 80, respectively. An average of 4.5 and 2.38 puparia respectively in fourth and fifth instar larvae were reared.