Butterflies lay almost a thousand eggs, but only a few of them survive. Most female butterflies lay eggs on leaves. A few of them release their eggs while flying. One such example is the grass feeding butterflies. Some species lay one egg at a time, others lay eggs in small clusters, while others lay hundreds at a time.

First, the female butterflies choose the correct food plant for their caterpillars. Then they walk on the leaves carefully, to make sure it belongs to the right plant species. The newly laid eggs are yellowish-white in color. The eggs are protected by a hard-ridged outer layer of shell, called the chorion. This is lined with a coating of wax, which prevents the egg from drying out before the larva has had time to fully develop.

The egg stage lasts a few weeks in most butterflies, but eggs laid close to winter, go through a resting stage, and the hatching may take place only in spring.