Abstract
In order to clarify the effect of vegetation on ridges and ridge-mowing techniques on the population density of wolf spiders, we investigated the seasonal changes in the population density of wolf spiders in rice paddy fields and in the ridges between these fields. A greater number of wolf spiders were detected in the ridges on which the Gramineae Imperata cylindrical and Echinochloa crus-galli grew than in the ridges on which the Cyperaceae Fimbrisytlis miliacea and F. dichotoma grew. The number of wolf spiders hardly changed from August to September in the field where the ridges were not mowed. In contrast, the number of wolf spiders increased considerably after the ridges were mowed, and these spiders were observed under the cut plants in the ridges. However, the number of wolf spiders did not increase when the ridges were mowed at a height of 20 cm from the ground.
