[Objectives]  To clarify the cause of the red spot on Pyrus sinkangensis, identify the scale insects that damage the fruit of this species and how these spread. [Methods]  The damage caused by two kinds of scale insect were observed during the development of pear fruit by artificially inoculating P. sinkangensis at fixed points. The subsequent spread of these pests was monitored using the hanging yellow board method. [Results]  During the the fruit growing period, second generation nymphs of Quadraspidiotus perniciosus crawl onto the fruit and cause the spots visible on the surface of fruit in the middle of July. Dark red spots occur where the fruit is reddish and dark green spots when damage occurs in unpigmented areas. Early stage fruit are harmed by 1^st instar nymphs of Quadraspidiotus slavonicus (Green). 1^st instar nymphs of this species drift on the wind to pear leaves and fruits from adjacent poplar forests causing red spots to appear on the surface of fruit in late May and early June. When the wind scale was about 2-3, 1^st instar nymphs of Q. slavonicus dispersed a maximum of 50 m and the mean number caught on yellow sticky boards under these conditions was 0.011 per one cm². When the wind scale was about 5-6, 1^st instar nymph could disperse up to 150 m, and the mean number caught on yellow sticky boards was 0.239 per one cm². [Conclusion]  The red spots on young fruit of P. sinkangensis are caused by 1^st instar nymphs of Q. slavonicus. Important factors influencing the spread of this pest to P. sinkangensis orchards are the height of the poplar forest zone, the wind force, and the number of insects. Spots on pears during the P. sinkangensis fruit growing period (mid-July) were caused by 2^nd generation nymphs of Q. perniciosus.