When it is ready to hatch, the tiny caterpillar starts to eats its way out of the egg. Once it has made a hole big enough, it crawls out onto the leaf. The newly hatched caterpillar will often first eat the rest of the egg shell, as it contains nutrients that will help it grow.
The caterpillar will then start to eat the swan plant leaf it is sitting on. At this stage, the caterpillar doesn’t eat the whole leaf the way older caterpillars do. Instead, it eats the top (or bottom) layer of leaf cells, leaving the fine veins of the leaf intact.
This video shows the tiny caterpillar hatching from its egg. The video is sped up to 2.5 times the actual speed.