What kinds of light attract moths best?
Multiple studies have found moths along with most other insects to be significantly more attracted to lamps that emit smaller wavelengths such as ultraviolet (UV). Some species of moth appear to be more attracted to shorter wavelengths than others. The visibility of the light to the moth, the distance between the moth and light, and the brightness of the light are also contributing factors in whether the moth will be attracted to light.
Why Moths are Obsessed with Lamps | Nat Geo Wild



Langevelde et al. found that actinic lamps with a mean weighted wavelength of 382 nm (lamp type a) were the most attractive to moths in both abundance and species richness when compared to other lamps that emitted longer wavelengths. The lamp types used along with the data they collected are displayed below:



References &amp; Further Reading
Hsiao, H. (1972). The attraction of moths (Trichoplusia ni) to infrared radiation. Journal of Insect Physiology, 18(9), 1705-1714. doi:10.1016/0022-1910(72)90100-x
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Owens, A. C., &amp; Lewis, S. M. (2018). The impact of artificial light at night on nocturnal insects: A review and synthesis. Ecology and Evolution, 8(22), 11337-11358. doi:10.1002/ece3.4557
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Somers-Yeates, R., Hodgson, D., McGregor, P. K., Spalding, A., &amp; Ffrench-Constant, R. H. (2013). Shedding light on moths: shorter wavelengths attract noctuids more than geometrids. Biology Letters, 9(4), 20130376-20130376. doi:10.1098/rsbl.2013.0376
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Truxa, C., &amp; Fiedler, K. (2012). Attraction to light - from how far do moths (Lepidoptera) return to weak artificial sources of light? European Journal of Entomology, 109(1), 77-84. doi:10.14411/eje.2012.010
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Van Langevelde, F., Ettema, J. A., Donners, M., WallisDeVries, M. F., &amp; Groenendijk, D. (2011). Effect of spectral composition of artificial light on the attraction of moths. Biological Conservation, 144(9), 2274-2281. doi:10.1016/j.biocon.2011.06.004
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