[Objectives]  Simultaneous color contrast is a phenomenon which describes how the visual perception of a colored target can be affected by the other colors or patterns. The study of simultaneous color contrast in insects has stronger ecological relevance than studies using plain colored targets or mono-wavelength light as test stimuli, and will contribute to the optimization of colored boards for trapping insect pests. [Methods]  Laboratory bioassays and field trapping experiments were used to investigate simultaneous color contrast in alate Myzus persicae by recording if these were attracted to, or repelled by, combinations of different colors. [Results]  The interaction between background and target color was extremely significant. Among the 64 patterns prepared using eight saturated colors, the most preferred were saturated yellow (R=G=255, B=0) and saturated green (R=B=0, G=255). The addition of any spots of another color on a yellow or green background significantly reduced their attractiveness relative to background color alone, even when the composite patterns combined yellow and green. Moreover, the most repellent pattern was a red background with black spots, which is similar to the pattern on the elytra of common lady beetles. A series of paired tests confirmed that this repellence was a true simultaneous color contrast effect. The pattern of a black background with red spots was also significantly repellent (black background + red spot vs plain red: t₉ = 13.18, P＜0.000 1; black background + red spot vs. plain black: t₉ = 2.14, P = 0.061 3), but less so than the pattern resembling lady beetle elytra (t₉ = 3.97, P = 0.003 3). The optimal parameters (background redness=192, spot gamma value = 0, spot diameter ≤ 2 mm) of the repellent pattern were determined using an orthogonal design experiment. The results of a field trapping experiment demonstrated that the simultaneous color contrast effect of a red background and black spots was significant when the patterns were added to a less attractive green board, but not so when the patterns were added to a highly attractive yellow board. [Conclusion]  The color preferences of alate M. persicae are affected by simultaneous color contrasts. The most attractive color was plain, solid yellow, followed by plain, solid green. Composite patterns of these two colors were significantly less attractive than the corresponding plain colors. The most repellant color pattern resembled the pattern on the elytra of common lady beetles. However, results of a field bioassay indicates that alates are only repelled by this pattern when it is on a green background.