How to Determine the Sex of a Luna Moth

Compare the antennae size of the adult moths. The main method for discerning the sex of adult luna moths is antennae size. Males have larger and bushier antennae than females.

Consider the coloring of the moths. Female luna moths have more of a blue-green cast to their coloring compared to males. Males tend to have a yellow-green color.

Examine the surface of the cocoons of luna moth pupae for details that allow you to distinguish the sex of the moth-to-be; the ventral surface of the cocoons of females has two longitudinal notches located on the fourth and fifth abdominal segments.

Note the time of emergence. Male luna moths will usually emerge from their cocoons several days before the female moths.

Take into account any geographic differences in appearance. These should be common to both sexes. According to the University of Florida IFAS Extension, moths in the south tend to be smaller.

Be aware of differences in coloring due to the time of emergence. These differences can make it more difficult to discern male from female moths in later broods. Luna moths may produce more than one generation in a year, with the number of generations increasing the further south the population of moths. In the north, the adults appear in June or July, while in Louisiana and Florida, luna moths are present throughout the year.

According to the University of Florida IFAS Extension, adult moths from spring broods tend to show deeper green coloring and reddish-purple wing margins, and those from later broods have a more yellowish-green coloring with yellow wing margins. In both sexes, the hind wings feature long swallow-tails with pink wing margins on moths appearing in spring and yellow margins on those appearing in summer.