The Japanese giant silkworm Caligula japonica Moore is an emerging defoliator pest of forest and fruit trees, causing severe economic losses in East Asia. To identify biological control agents for this pest, we comparatively evaluated six indigenous eupelmid egg parasitoids (Anastatus fulloi, A. gansuensis, A. japonicus, A. meilingensis, Mesocomys albitarsis and M. trabalae) from China, in terms of their performances (number of parasitized eggs, developmental time, offspring emergence and sex ratio) on C. japonica eggs of four different ages (0, 10, 20 and 30-d old). Results showed that all six parasitoids readily parasitized C. japonica eggs of all tested ages, but A. japonicus was the most efficient species based on the number of parasitized eggs, followed by M. albitarsis and M. trabalae, and the other three parasitoid species. All four Anastatus species parasitized more old than young eggs, while M. albitarsis did not show a strong host age preference and M. trabalae parasitized the oldest less than young eggs. For all host ages, developmental time was longest in A. gansuensis and shortest in M. albitarsis, offspring emergence was high (> 90%), and progeny was strongly female biased (> 70%) among all parasitoids except for A. gansuensis which produced all female progeny. Portions of A. japonicus offspring (< 13.1%) entered diapause as pre-pupae. Accordingly, A. japonicus, M. albitarsis and M. trabalae were identified as the most suitable agents against C. japonica. This information may also help improve rearing and field-release protocols, in terms of host age-related effects on these parasitoids.