Surface damage to Japanese pear [Pyrus pyrifolia] cv. Nijisseiki fruit by two-spotted spider mite, Tetranychus urticae Koch

A high rate of abnormally stained fruit was produced by introducing the two-spotted spider mite, Tetranychus urticae Koch, into bagged fruit of the Japanese pear cv. Nijisseiki, especially during July and August. Many punctures made by the spider mites were observed on the stained lesions using SEM. This is a new type of damage called “usuzumi” (gray stain), caused by the two-spotted spider mite.