Colony composition,social behavior and some ecological characteristics of the Korean wood-feeding cockroach (Cryptocercus kyebangensis)

Korean populations of the genus Cryptocercus occur in forested mountains throughout South Korea. They live in monogamous associations in which parents care for their young in complex woody galleries. Single paired adults (23.2%) and one or both parents with their offspring (28.1%) were found most frequently in the field. Among single-parent families adult females (6.7%) were observed more frequently than adult males (1.4%). In families with single or both parents, the mean brood size was 21.6+/-9.4. Oothecae were observed from mid-June to the late July. Oothecae were found in the galleries of only paired adults and never found in families with nymphs. The mean number of eggs per female was 73.7+/-29.8. Most of neonates grew to the third or fourth instar prior to the winter. During the winter, C. kyebangensis in the field remained almost frozen in their galleries, but ones kept in the laboratory continued to grow during winter. Some characteristics of proctodeal feeding behavior are also described based on laboratory observations. We propose that the cold temperate climate, especially of the winter season, is one of the most important causes for the evolution of unusual life history of Cryptocercus including delayed development of nymphs.