Hummingbird and Butterfly Gardening: Watched monarch cat turn to chrysalis today, 1 by Sheila_FW

Sheila_FW wrote:
This is the underside of a Monarch's wing, but you can still tell the difference in male and female. The top one is female, with straight even cell markings. The lower one you can see a widening of the black cell edge where the dot is on the dorsal side.

It is also a way to tell the sex inside the chrysalis, but I don't have the pics close enough for that. Nor do I feel I need to know in advance LOL!