A question often asked, “how can you tell it’s a male or female Monarch Butterfly?”
The difference is easy to see when you are looking at the upper side of the butterfly’s wings. On the hind wings of the male Monarch are two black dots, one dot on each hind wing. These dots are actually pockets filled with pheromones, or “love dust.” When the male and female meet, he sprinkles his love dust, and if she is receptive, the pair will join abdomen to abdomen, where they stayed coupled together for several hours.
You can also see the difference by comparing wing veination. The females wing veins are thicker and smokier, the male’s wing veins are thinner.
During the summer breeding months, you can often tell the difference by behavior, especially when near a patch of milkweed. The males vigorously fly about looking for females, whereas the females are more slowly flitting and hovering around the foliage, looking for places on which to oviposit her eggs. Their behavior during the fall migration is such that both male and female are intently drinking nectar, building their lipid reserves for the long journey south.
Next time you see a Monarch in your garden, have a look and see if you can tell whether male or female.