Caterpillars get their start as eggs laid by other caterpillars on plants, according to About.com. Before caterpillars turn into butterflies they lay their eggs in appropriate locations to start the next generation.
The start of a caterpillar is one much like other bugs in that the parent lays eggs, and after a time, the larva come out of the eggs. The larva eat these egg shells as their first meal and then move on to eating constantly. As a matter of fact, a caterpillar can eat as much as 27,000 times its body weight within its life cycle, which lasts only a few weeks. The caterpillar continues to eat to build strength, which allows it to grow to maturity and begin laying new eggs. This starts the process over again, giving life to a new generation of caterpillars. Although there are many different types of caterpillars, they have virtually the same process for life. Some prefer cooler areas and lay their eggs high in trees in nests that look like spider webs. Other caterpillars prefer low areas in the grass to lay their eggs in. Some caterpillars can take over trees with egg-filled nests that soon turn into hundreds of caterpillars.