Follow the life cycles

There are 4 stages in a butterfly's life cycle: the egg, the caterpillar or larva, the pupa and the adult butterfly. Here are some facts about them.

The egg
  • The female butterfly lays its eggs near some leaves, or on them, so that the caterpillars will have enough food to eat. Each butterfly has a favourite plant, called a host plant. Butterflies can ‘taste’ which plant they are on by using their feet.
  • The eggs of different butterfly species look quite different. They are all tiny but they can be round, oval or cylindrical. Their texture can be wrinkled or pitted, or it can be smooth and polished. The eggs are laid singly or in batches.
  • Some eggs will hatch after a few weeks but others won't hatch until the weather is warm. The length of time depends on the season and the species of butterfly.
  • Some butterfly eggs such as the Monarch butterfly can be poisonous.
The caterpillar
The caterpillar of a lymantriid moth

The caterpillar of a lymantriid moth

  • The newly emerged caterpillar is just a few millimetres long. As soon as it is born, it will start eating - first its eggshell and then the leaves of the host plant. It will eat almost non-stop until it has stored enough nutrients to become a pupa and later a butterfly.
  • The caterpillar is an eating machine. It has a pair of jaws for chewing plants, 8 pairs of legs and a long gut for digestion.
  • A fully grown caterpillar can be over a thousand times heavier than when it emerged from the egg.
  • As the caterpillar grows, it sheds its skin like a snake. The more it eats, the bigger it gets until its skin becomes too tight and splits open. Underneath is a new skin, bigger than the old one. Most caterpillars grow 5 new skins in their life but some only grow 4 and a few grow as many as 9.
The pupa
  • Once it is fully-grown, the caterpillar stops eating and starts looking for a safe place where it will change into a pupa.
  • A cocoon provides most types of pupa with some protection from extreme temperatures. It also helps to stop the pupa from drying out and from being attacked by predators.
  • Female pupae contain higher proportions of fat and protein than male pupae.
  • Inside the pupa the caterpillar changes into a fully grown adult butterfly. When the butterfly is ready to emerge, the case holding the pupa splits open.
  • The process of changing from an egg to a larva to a pupa and then to an adult butterfly is called metamorphosis.
The wing of a peacock butterfly

The wing of a peacock butterfly

The butterfly
  • Once it has hatched out, the butterfly needs to wait until its wings are dry and unfolded before it can start flying around. It also has to wait for enough oxygen to pass through its tiny veins. It looks for sources of nutrients such as flowers to feed from and for other butterflies to mate with. The process is now complete and can start all over again.