Phototactic behavior toward ultraviolet light varies among nocturnal flying insects. By recording sex ratios of 28 southeastern US moth species, we tested the commonly held belief that UV light-trap collections of moths are significantly skewed toward males. Twelve species demonstrated a statistically significant male preponderance, but a wide range of sex ratios was found. Two of the 28 species demonstrated both significant male and female bias during different observation periods, illustrating the need to collect over the entire flight period. Since the sex ratio of collected organisms varies by species and by time, this must be taken into consideration when using light-trap collection to make population estimates and to gather information for conservation or control of any particular species.