Using electroretinogram recordings, the response of Lutzomyia longipalpis sandfly eyes to a range of wavelengths of light was measured, and spectral sensitivity determined. The eyes of both male and female adult sandflies were found to respond maximally to light in the ultraviolet region (at 340 nm) with a secondary peak in the blue-green-yellow region at 520 nm for females and 546 nm for males. The Mann-Whitney U test showed no significant differences between males and females at corresponding wavelengths.