none The effect on sex ratio of B. brevicornis progeny when male, female, and host larva (Sesamia cretica ) were placed together in different time sequences, was investigated. Placing a parasitoid female first, a male after 3 hours, and a host larva after 24 hours, yielded significantly the highest proportion of females (48%). In this case female/male sex ratio was 1:1 approximately, while other manipulations ranged from 1:4 to 1:20 (with preponderance to males). Techniques; Ecology; Population dynamics; Population structure Bracon bevicornis (Braconidae); Breeding techniques; Population sex ratio; Improved female ratio, breeding technique