A Closer Look at Butterfly Pupa

Pupa is an amazing stage in the life cycle of a butterfly. This is the stage through which the caterpillar turns into an adult, with a completely different appearance and structure. This is called complete metamorphosis. There are several differences between the caterpillar and the adult: the adult has wings while the caterpillar has none; the caterpillar has 8 pairs of legs while the adult has only three; the caterpillar feeds on solid food (such as leaves) with its mouthpiece while the adult uses a long tube to sip fluid (such as nectar). The differences between the two are miraculous, because in this way the two will not compete for the same resources as they depend on different micro environments and food.

Total facelift
Before turning into a pupa, the caterpillar stops eating and looks for a suitable place, mostly under a leaf or on a branch, to make its pupa. It uses its silk to weave a thick mat and stabilise itself on the mat with its tail. This is the “pre-pupa” stage. After one day, the caterpillar sheds its skin, exposing only the pupa. Inside the seemingly quiet pupa, a revolution is underway. The organs of the caterpillar are broken down and rebuilt into new organs of the butterfly. When the “reorganisation” is complete, the pupa becomes transparent. You can just make out the adult butterfly’s wing pattern, and the butterfly is ready to emerge.

The eclosion is a majestic moment. Typically, it takes place from late at night, to early morning. The pupa splits open, and the adult crawls out with extreme care. The head, thorax and legs come out first. Then the whole body emerges. The newly emerged butterfly cannot fly, and this is the weakest moment of its life. The wings are folded, and waiting for the body fluid to fill them up. The butterfly must be very careful. If it falls onto the ground at this time, its wings will never be able to stretch out. With the wings stretched out and hardened, the butterfly can now fly high into the sky!

Pupa of a Birdwing butterfly

Plain Tiger (Danaus chrysippus) entering pre-pupa stage

Immobile but variable features
The forms of pupae differ. Pupae of Danaids, Nymphs, Duffer & Fauns and Browns hang upside down with head down and tail up; these are "suspended pupae". Pupae of Swallowtails & Birdwings, and Whites & Yellows have their head up and tail down, with a silk bundle in the middle. These are "girdled pupae".

The pupae are immobile. Hence, they are equipped with different ways to protect themselves. Some use camouflage to hide in nature; some can even change colour according to the environment. When the cocoon is made on a leaf, the colour is green; when it is made on a branch, the colour is brown. However, not all species like to hide. Some are brightly coloured to warn predators that they are poisonous. Euploea’s pupae have metallic colours, which can scare predators while reflecting light for concealment.

Suspended pupa of Plain Tiger (Danaus chrysippus)

Girdled pupa Tailed Jay (Graphium agamemnon)