Abstract: Ceroplastes ceriferus (Fabricius) is one of the most serious pests of Cedrus deodara (Roxb.) Loud and other garden trees.In order to control the pest,its is very important to forecast accurately amount and abounding in incubation period of nymph.In 1997,by studying on weight,length ovipositing amount of the latter and feeding in condition of various and constant temperature in Hefei,results were as follows:the mean weight x1=0.1103±0.0849g,the length x2=7.027±0.202mm,oviposinting amount y=4880.54 440.53.There were relations between ovipositing amount and weight and length.Detail regression equations were respectively y1=-571.25+50078.3x1,r1=0.9719;y2=-10356.46+1983.39x2,r2=0.8436.The initial temperature for the period of development of the egg C and effective accumulated tempterture K were found.They were C=10.251.53 or C=9.940.19 and K=165.156.96 DD or K=141.512.15 DD.Based on those parameters,the forecast is quite successful.