Insects start their lives as eggs, laid by female insects. When young insects hatch, they are called larvae (larva is the word for just one baby insect). Some larvae look like mini versions of the adults, like grasshoppers. The larvae of some insects look very different from the adults; think about how different caterpillars and butterflies look.
The larvae eat lots of food, and grow. Some get bigger until they become adults, like grasshoppers. Others, like butterflies and moths, and have another stage in their lifecycle: pupation. When caterpillars pupate, they metamorphose (change) into an adult that looks very different. They come out of their pupae as adults with wings.
After male and female adult insects have mated, the female may lay eggs, and the lifecycle starts again.