Caterpillars are the larvae stage of butterflies and moths.
People who study butterflies and moths are called lepidopterists
and the study is called lepidoptery. It is a subset of entomology,
the study of insects.
Caterpillars are larval form of the order Lepidoptera.
Caterpillars eat plants called host plants, while the adult
butterflies drink nectar plants. If caterpillars don't have access
to their specific host plant, they wont eat anything and thus they
will die.