An Attempt to Use Distribution of Insects as an Index for Assessment of Urban Environment

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Three residential suburb areas (Owada (Moriguchi city), Makino (Hirakata city) and Nagaodai (Hirakata city)) near Osaka city were subjected, Green area estimated from LANDSAT data by a personal computer were estimated 7.3%, 14.0% and 51.5% in. Owada, Makino arid Nagaodai, respectively. The distribution of exuviae of cicada at university campuses in these 3 areas was investigated. Four kinds of the exuviae were collected and Graptopsaltria nigrofuscata and Cryptotympana facialis were occupied more than 99% of those. The percentage of Cryptotympana facialis was 66% at Owada, 34% at Makirio and 4% at Nagaodai ; Cryptotympana facialis was much more common in the more urban sites. Butterfly communities were monitored by a transect-count method at these areas in 1996 and 1997. Nine species in Owada, 21 species in Makino, and 30 species in Nagaodai were observed in the two years. Seven species such as Pseudozizceria maha were commonly observed in all the areas and occupied 99.4, 96.2 and 81,3% of the butterflies in Owada, Makino and Nagaodai, respectively. Sunose's BI index distinguish the 3 areas separately and estimated Owada, Makino arid Nagaodai as a suburban to urban stage, a typical residential suburb and a rural-suburb stage, respectively. In Katsura, a residential suburb near Kyoto city, butterfly communities were monitored by a transect-count method in 1997 and 1998 and the records of observation or collection of butterflies in 1991 to 1996 were summarized, The population density of each species observed in the 2-year-transect was positively associated with the previous records. These results indicate that the El index and the percentage of the 7 common species in butterfly communities as well as the percentage of Cryptotympana facialis in cicada communities are available as indices of urban biological environment, and that two-year-transect is necessary to elucidate a butterfly community in a residential suburb area.