Euplectrus xanthocephalus Girault is an ectoparasite of Spodoptera litura. In the experiment the parent sex ratio of the ectoparasite on the host significantly affects some biology characters of the parasite such as the longivity of adult, the number of laid eggs daily and the number of laid eggs of one female in its life, the sex ratio of progeny, the parasitism of this host larvae by one parasite female. On the other hand, the parent sex ratio unclearly influences on the number eggs laid on one host larvae and on surviving of preimaginal phases of parasite progeny. The average female's life span was 11.30 days with the sex ratio 1 female:1 male, and 13.30 days with the sex ratio 2 females:1 male and 16.30 days with the sex ratio 3 females:1 male. Female's reproductive capacity is 3.16 eggs per day with the. sex ratio 1 female:1 male
this is higher than the fecundity of the female with the sex ratio 2 females:1 male
a female lays 2.94 eggs/day. The female lays 2.03 eggs per day with the sex ratio 3 females:1 male. The sex ratio (female:male) of progeny is 1.92:1 with the parent sex ratio 1 female:1 male
the progeny sex ratio 1.46:1 with the parent sex ratio 2 females:1 male and the progeny sex ratio 1.09:1 with the parent sex ratio 3 females:1 male.