Encarsia transvena is a potentially useful parasitoid of Bemisia tabaci (Gennadius) in India. Development, host preference and parasitism by the parasitoid were studied at 25–30°C and 70–75% RH. Results showed that E. transvena is a solitary, arrhenotokous, heteronomous, autoparasitoid. Female eggs are laid internally in whitefly nymphs and develop as primary parasitoids. Males develop as hyperparasitoids, either on females of their own species or on other primary aphelinid parasitoids. Both sexes have an egg, three larval, a prepupal and pupal stage. Development from egg to adult took 11.3–15.0 d for females and 12.1–14.6 d for males. Superparasitism was common under cage condition, either on specific females or other primary parasitoids. E. transvena females were able to develop in all B. tabaci nymphal stages but preferred the third and early fourth instars. Oviposition and developmental periods of the parasitoid were longest on first and fourth (late) instars of B. tabaci. The highest percentages of parasitization occurred in third instar and fourth (early) instar B. tabaci and the lowest percentages in first and fourth (late) instars. The information should be useful in designing mass rearing protocols and in release trials for suppression of B. tabaci populations.