It's hard to tell size from the picture below, but we recently discovered The Littlest Monarch in My Florida Backyard. We found it a few evenings ago, obviously just emerged from chrysalis (you can see it in the bottom right corner of the picture in the background), drying its wings and getting ready to fly. It was at least one-third smaller than an average monarch butterfly, more the size of a buckeye or white peacock.
There could be a few reasons for the small size of this monarch. Most likely is the limited food supply this time of year. Though we have some milkweed in the garden for monarch caterpillars to eat, the dry and cool season has limited its growth. This gives the caterpillar less to eat, causing them to be smaller overall when they enter chrysalis. Butterflies are fully-grown when they emerge, and this one will not grow or change size during the few weeks of its life, but as long as it has the ability to fly, eat, and mate (which this one seems to), it should do just fine.
Winter is a time to savor every bit of wildlife in My Florida Backyard, no matter the size. We feel fortunate to have butterflies of any size in My Florida Backyard in January, especially when snowstorms rage up north!