How do you tell if a monarch butterfly is boy or girl?

There are a few ways to tell if a monarch butterfly is male or female. One way is to look at the underside of the wings. Males have a black spot on the hind wing that females don't have. Another way to tell is by the shape of the abdomen. Males have a pointier abdomen than females. Finally, you can also tell the difference by the color of the wings. Males have brighter orange wings than females.