[Survey on historical Oncomelania snail environments in Changshu City]

The historical Oncomelania snail environments discovered since 1976 were surveyed in Changshu City, Jiangsu Province. There were 425 foci of historical snail environments that were discovered in 16 towns, the snail area was 124 893 m2. The transformation rates of historical snail environments and of the snail area were 76.71% and 86.92%, respectively. The transformation rates of the ditches, the ponds and the land were 98.17%, 97.93%, and 95.04%, respectively, but the transformation rate of river channels was only 28.23%. We still need to strengthen the environmental transformation of historical snail river channels.