An experiment was conducted to investigate types of injury inflected by the stone leek leafminer, kiriomyza chinensis Kato on welsh onion. A feeding scar made by an adult female was a hole round in shape, with diameter of 0.08 mm and 0.48mm in lesion, resulting in a white spot, many of which often vertical dotted lines on a leaf. Egg spots were oval with 0.1¡¿0.14mm in size, one or several of which often form a V-shape in group. Feeding by adults began immediately after emergence and was very active from 4 th to 5th day. Oviposition was done from 2nd to 6th day after emergence. In both feeding and oviposion , they were more active in the day time. larvae after emergence crawled up the leaf at first, and then moved up and down to feed on mesophyll.