This specific plant material is referred to as the ' larval host plant ', the ' caterpillar host plant ', or the ' butterfly host plant '. One larva's staple is another one's poison. What makes a butterfly species abundant in one area and unseen in another often has something to do with the availability of caterpillar host plants. In order for a butterfly species to survive in any location, ample food must be available for its caterpillars. Without caterpillars, there couldn't be butterflies.
Most butterflies live for just a few weeks or a few months.
For the species to survive, therefore, the females in that species must lay fertile eggs before their short lives end. And to ensure the survival of the caterpillars that will emerge from the eggs, eggs must be laid on or near the appropriate larval host plant. When the eggs hatch, the tiny caterpillars usually eat their egg casings and then begin to feed on the host plant. Each finds a sheltered location to pupate. Later a butterfly emerges from the chrysalis.