Studies were conducted on the endoparasiteApanteles machaeralis Wilkinson (Hymenoptera: Braconidae) to determine its biology whenDiaphania indica (Lepidoptera: Pyralidae) is its host. Eggs were deposited in host larvae and increased greatly in size before hatching. The first instar larva was very active with functional mandibles, whereas the second stage larva was quiescent. The third instar larva spins its cocoon outside the body of the dead host. Mean development time from egg to adult was 12·63 days at 29·25 ± 1·82°C and 59-66% RH. There is no preoviposition period. The sex ratio was 1:1·22 (males/females). Mean adult longevity was not significantly different for males (9·31 days) and females (11·68 days).