Male or female?
A female monarch has thicker black veins on her wings on the orange. This is hard to tell if there's not a male next to her to compare. A male is easy to identify. Look at the pictures below and you can see two black dots on the inside vein of the lower wing. These are pheremone producing glands that the male may use to attract females. It's harder to see the dots from the underside of the wing, but if you look carefully, you can see a blemish on the inner vein.