Tube-nesting wasp and bee biodiversity was studied in a new town in the hilly area of Sanda City, Hyogo Prefecture, for use in discussing guidelines for conserving these satoyama (rural forest) insects in the fragmented forests. A total of 77 bamboo trap-nests were set in the new town, along the environmental gradient- fragmented forests in the surrounding and central zone, grass fields, green belts and residential zone. 13 species were obtained, among which Auplopus carbonarius, Anterhynchium flavomarginatum and Isodontia nigella were the most frequent. The species diversity was the highest in the fragmented forests, and lowest in the green belts. The distribution pattern showed that the insect presence or absence at trap-sites were accounted for by the coverage of forest area and the degree of isolation (distance to surrounding forests), respectively. On the basis of these data, the methods of conserving the insects in the fragmented forests are discussed.
