NESTING SITES OF THE JAPANESE VESPA SPECIES

Miscellaneous observations on the nesting sites of the genus Vespa in Japan are presented. A total of 350 nests of 6 Vespa species, i.e. V. analis insularis, V. xanthoptera, V. simillima, V. crabro flavofasciata, V. tropica pulchra and V. mandarinia latilineata, were observed from 1957 till 1969. 1. It is recognized that the nesting site preference of Vespa differs characteristically with species, being classified into the open place and covered place types. 2. V. analis insularis and V. xanthoptera belong to the species of the open place preference. V. ana'is insularis nests only in open situations above ground, and 74 out of 86 nests, or 86.0%, hung from bushes or trees near the ground. On the other hand, V. xanthoptera builds nests both in the open place (80.7%) and in the covered place above and under ground (19.3%), 113 out of 166 nests, or 68.1% having been attached to the beams or the eaves of human buildings, though is variable in nesting site selection than any other congeneric species in Japan. 3. Three species, V. crabro flavofasciata, V. tropica pulchra and V. mandarinia latilineata, prefer only for covered situations, belonging to the species of the covered place preference. V. crabro flavofasciata and V. tropica pulchra make their nests either in restricted cavities or in ample spaces both above and under ground. On the other hand, V. mandarinia latilineata nests only in underground situations. 4. As to V. simillima inhabiting Hokkaido, Northern Japan, it is not certain for the lack of sufficient data whether it prefers the open place or the covered place, though the nests were found from both open and covered places above ground. 5. The general shape of the nest envelope changes between the species of the open place preference and those of the covered place preference. In the first group with V. xanthoptera and V. ana'is insularis, and in addition with V. simillima and V. dybowskii, the envelope is usually thi ck, covering the nest completely. On the other hand, in the second group with V. crabro flavofasciata, V. tropica pulchra and V. mandarinia latilineata the envelope is thin and is always omitted at the bottom of the nest. 6. No particular relation between nesting site and direction to which the nest faces is found. 7. Height of the nesting sites from the ground differs with species. V. analis insularis usually builds its nest at lower levels about 2 m from the ground (84.5%). On the other hand, 79.5% of the aerial nests of V. xanthoptera were built 2-7 m above ground. Nests of the species of the covered place preference, V. tropica pulchra and V. crabro flavofasciata, are made at lower levels about 4.5 m from the ground. Subterranean nests of 4 species, V. xanthoptera, V. tropica pulchra, V. crabro flavofasciata and V. mandarinia latilineata, are all located at places within 0.6 m under the ground surface. 8. Nests built in covered situations above and under ground are situated 3 to 420 cm distant from the cavity entrance, and individuals of the nest followed the route or the tunnel to reach the nest without flying. 9. Rebuilding in the previous nesting site was observed intraspecifically for V. xanthoptera, V. crabro flavofasciata and V. analis insularis, and interspecifically between V. crabro flavofasciata and V. xanthoptera. 10. Some instances on the concentration of nests within limited areas were observed both intra- and interspecifically.