Abstract
A device for quantitative evaluation of the spider mite webbing was developed. Using this device the relationship between walking behavior and webbing was examined with adult females of tetranychid mites, Tetranychus urticae KOCH and Panonychus citri (MCGREGOR). Also the behavior of these species on the experimental surface facing downwards were recorded by means of the inverted-type projector with trans-illumination. Both tetranychid mites fell down frequently from the experimental arena in the absence of disturbance, but they were suspended simultaneously with their threads. This phenomenon is suggested to relate to “roping” or “parachuting” behavior reported by many authors. Furthermore, the locomotive velocity and the proportion of walking, resting and suspended time were estimated. The webbing was closely related to the walking behavior in both species and the female of these mites was postulated to produce silk threads always during a walking.
