When the eggs hatch, tiny caterpillars begin feeding and growing. Its first meal is usually the eggshell, which provides it with important nutrients. Then it will begin eating the host plant. Almost all caterpillars eat leaves but some eat stems, roots, fruits, seeds, seed pods or flowers. They will eat only the host plant and will not move to any adjacent plant of a different species – even if it runs out of food. As they eat and their bodies expand, their skin (an exoskeleton with a limited stretching capacity) becomes tight and eventually splits and sheds, revealing new skin beneath. This is called molting and occurs several times as the larva grows.