Here, we describe the biology of a relatively new pest cockroach species in Southeast Asia, Symploce pallens (Stephens) (Dictyoptera: Blattellidae). S. pallens collected from Penang Island, Malaysia, were used for the biological parameter studies and were observed for molting and reproduction events. Nymphal development took 118.2 ± 1.7 d, with a mean of 9.5 ± 0.1 molts. The oothecal incubation period was 36.1 ± 0.2 d. Females produced a mean of 16.0 ± 10.2 oothecae, with mean 17.6 ± 0.1 nymphs per ootheca. Nymphal survivorship per ootheca was 90.4%, and 90.7% of nymphs achieved adulthood, The sex ratio did not deviate from 1:1. The mean longevity of adult males and females was 309.3 ± 7.6 and 322.6 ± 14.8 d, respectively. In general, S. pallens exhibited higher oothecal production and longer nymphal development and longevity compared with the German cockroach, Blattella germanica (L.).