[Objectives]  To identify diagnostic morphometric features of insect species that allow the sex of individuals to be reliably determined is of great importance to the remote identification of insect species using image processing techniques. The aim of this study was to use image acquisition technology to identify the parameters distinguishing female and male adults of the pear lace bug Stephanitis nash Esaki et Takeya. [Methods]  Morphometric characteristics of adults were extracted using the software BugShape v1.0 developed by IPMist Lab. at China Agricultural University and the data were analyzed in SPSS v22.0. Images of adults were created with a flatbed scanner (Epson perfection v370) with a transparency adapter. Fifty samples of each gender were measured at three scanning resolutions (1 200 dpi, 2 400 dpi and 4 800 dpi). [Results]  Scanning resolution had a positive effect on some parameters such as perimeter, mesothorax width (MW), and the mesothorax width /abdomen width (MW/AW) ratio, which increased with increasing resolution. Body length/abdomen width (BL/AW), and MW/AW) ratios derived from both automatically measured (area, equivalent radius (ER), eccentricity, compactness and circularity), and manually measured variables (MW, AW, the body length/mesothorax width (BL/MW), significantly differed between female and male adults. At 4 800 dpi scanning resolution, the BL of the pear lace bug was about 2.25 mm and female MW and AW were 0.02 mm and 0.19 mm, respectively, longer than those of males using manually-measured parameters. At 1 200 dpi resolution, discriminant accuracy based on cross validation was 99% using manually measured variables to discriminate the sexes, and 79% using automatically measured variables. However, using both kinds of variables increased the accuracy to 97%. [Conclusion]  1 200 dpi is the best resolution for discriminating male and female pear lace bugs with image processing technology. Some morphometric variables differ significantly between the two sexes, and can therefore serve as standard diagnostic criteria for sexing this species.