These larval forms usually live in different habitats, eat different foods, and assume a body form completely different from that of their parents. The larva feeds and grows, molting its skin periodically. At some point larval growth is completed, the larva stops feeding and builds a case or cocoon around itself. In this nonfeeding condition it is called a pupa or chrysalis. Other species undergo a more gradual process, in which the newly hatched young are more similar to the adult but are small in size, lack wings, are sexually immature, and may differ in other, relatively minor ways as well.
Insects are incalculably valuable to man.
Usually, we think of them in a negative context. Insects eat our food, feed on our blood and skin, contaminate our dwellings, and transmit horrible diseases. But without them, we could not exist. They are a fundamental part of our ecosystem. There is no general agreement on the details of how different groups of insects are related.