There is more blue on a butterfly’s wings … does that mean it is a male or a female?
In the United States …
In general, if the butterfly has a flat blue color, such as in Black Swallowtail butterflies, females have more blue.
In general, if the butterfly has a metallic blue color, such as in Pipevine Swallowtail butterflies, males have more blue.
Take a look at these photos!
Comparisons must be done WITHIN the species.
Females of some butterfly species, such as the Tiger, have a good bit of blue on their hind wings. Males have very little blue.
Females of other species, such as the Palamedes, have very little blue on their hindwings. Males have less or none.
Spicebush females are much like Tiger females. There is a good bit of blue on their hindwings. Most male Spicebush Swallowtail butterflies are more green than blue.
Pipevine Swallowtail males have a large patch of brilliant metallic blue on their hind wings. Female Pipevine Swallowtail butterflies have very little actual blue. Their hind wings are more of a metallic shiny black color.
Great Purple Hairstreak butterflies; males have more metallic blue and females have less metallic blue.
Many of the Hairstreak species are the same; males have more blue.
Remember – compare WITHIN the same species, not from species to species.
(Metallic blue isn’t color on the wings; it’s a refraction of light in a different manner than most blue colors. It’s an interesting online study. We encourage you to look up information about the blue that is in butterflies like the Blue Morpho and Pipevine butterflies!)