Abstract  [Aim]  To identify the best light wave-lengths for trapping the tomato leaf miner Tuta absoluta. [Methods]   Wave-lengths that attracted the tomato leaf miner were identified using an insect phototaxis measurement device. The effectiveness of different wave-length and light intensity combinations were then compared using a specially developed LED light trap. [Results]  The light wave-lengths tested could be ranked in order of attractiveness as follows: 380-385 nm > 410-420 nm > 390-395 nm > 430-435 nm > 420-425 nm > 365-370 nm. The more attractive wave-lengths were concentrated in the purple region of the spectrum. The most attractive wave-length to female moths was by 410-420 nm, followed by 380-385 nm. Male moths were most attracted by 380-385 nm, followed by 420-425 nm. Female moths had a stronger phototactic response than male moths to the same light wave-length. After external light interference was excluded, phototaxis first increased, then decreased, with increasing light intensity. Different intensities (12, 16, and 20 W) of 385 nm LED light traps were found to be the best for trapping tomato leaf miner moths in a greenhouse. [Conclusion]  Adult tomato leaf miner moths, and especially adult females, are strongly attracted to 380-385 nm purple light. Phototaxis of the tomato leaf miner first increases, then decreases, with increasing light intensity. The use of purple LED light traps can effectively reduce the population of tomato leaf miner moths in greenhouses.