The Monarch butterfly (Danaus plexippus) is a milkweed butterfly (subfamily Danainae), in the family Nymphalidae. It is perhaps the best known of all North American butterflies.
The Monarch is famous for its southward migration and northward return in summer in the Americas which spans the life of three to four generations of the butterfly. Thanks to my daddy Paolo, he's very fond of butterflies. When I asked him which kind of butterflies were the ones on the gown, he immediately reconized them.
Source: wikipedia.com, daddy :-)
Image source: vogue