A light emitting diode (LED) color ray was used to determine the most effective light color to capture the West Indian sweet potato weevil, Euscepes postfasciatus (Fairmaire). Preference tests were conducted using four colors of LED ray (blue, green, yellow and red) at fixed light quanta in the laboratory. The weevils preferred the green LED to the three other LEDs. The effectiveness of a green LED trap was subsequently compared with that of a sweet potato root trap in a sweet potato field with mature potatoes and the green LED trap was confirmed to be applicable for monitoring of the number of weevil.