An integrated pest management program (IPM) relies on multiple management methods to reduce pest populations. Onion thrips (Thrips tabaci) have relatively few effective control methods, and non-chemical management tools, like plastic mulches, need to be developed. We tested 7 different plastic mulches in the field, including 3 silver mulches, to determine their effect on thrips populations. Thrips populations were recorded once a week and a spectrophotometer were used to measure spectral data. We found that not all the silver mulches were equally effective at reducing thrips populations, likely due to differences in achromatic cues recorded by the spectrophotometer. A subset of the mulches was then tested in a second field trial with or without a pesticide program. In addition to recording thrips populations, plant growth, along with temperature above and below the mulch were recorded for the second field trial. In the second field trial, red and diamond silver mulch reduced thrips populations similar to the pesticide program. Furthermore, the addition of a pesticide program provided synergistic control in most treatments. Finally, we conducted a no-choice lab experiment to determine the potential mechanisms of mulches on thrips population regulation. Thrips numbers, mulch and soil temperature, and plant growth were recorded after 13 days. The no-choice experiment revealed that mulches likely affect thrips populations through wavelength-specific induced changes. Overall, we found that silver and red mulches suppressed thrips populations as effectively as a season-long pesticide program, providing options for an integrated pest management program.