If you guessed Right, you are correct! The female Cabbage White butterfly has two black spots on their wings, compared to one black spot on the males.
But they have other distinguishing features we can’t see. Like the Sulphurs, Cabbage Whites have ultraviolet patches on their wings built from a nitrogen-rich pigment compound called Pterin. Males who have more contrast between UV and non-UV patches on their wings are more attractive to females, but this also puts them at higher risk of being spotted by a predator. Pterin being nitrogen rich means that males who eat more nitrogen as caterpillars have more attractive wings. Read more about this here (academic paper).
These spots aren’t just for attracting mates, they are also important for staying warm. A Cabbage White that ecloses from their pupa in a colder environment may have darker or larger black spots (melanization) than other individuals that eclose in warmer environments. This also means that the amount of black on the wing can change across seasons. Interestingly, the effect of temperature on the amount of black and location of the patch can change based on other factors like length of day and sex of the butterfly. You can read more about this research here (news article) and see the community science initiative, Pieris Project here.
Photo credit
Male Cabbage White by Ady Rosebrigg (iNaturalist)
Female Cabbage White by David Eberly (iNaturalist)
Ready for next weeks’ quiz? Click here!