Silverleaf whitefly (SLW) was used to induce the silvering of summer squash.The effect of silverleaf whitefly on photosynthetic pigment in the leaf and leafstalk of summer squash was studied.The amount of chlorophyll and the precursors of chlorophyll biosynthesis were analyzed.The activity of chlorophyllase (Chlase) in the silvered leaf and leafstalk were also measured.It was found that the amount of chlorophyll decreased with the increasing disease grade.Chl b in leaf after being infested by SLW was affected more seriously with the increasing grade,however,the Chl a in the leafstalk was affected more seriously.Chlase activity significantly increased with the increasing disease grade.