Apanteles ruficrus(Haliday), a gregarious braconid parasitoid, was reared fromChrysodeixis argentiferacollections taken in Queensland, Australia, and imported into the United States, where laboratory studies were conducted to determine its basic biology.A. ruficrusprefers 3-day-old larvae of the soybean looper,Pseudoplusia includensWalker, and develops in the cabbage looper,Trichoplusia niHübner, and the fall armyworm,Spodoptera frugiperda(J. E. Smith). It attacks at least four other lepidopterous larvae. Mean developmental time from oviposition to larval emergence is 13.2 days at 28°C. Pupal development time ranges from 3 to 6 days. Mated adult males and females live about 20 and 18 days, respectively, whereas nonmated males live 18 days and females 20 days.