When a caterpillar is big enough, it will form a chrysalis. During which stage of metamorphosis does this occur? (2 points) a Adult b Egg c Nymph d Pupa

The stage of metamorphosis this occurs is called the PUPA stage. The correct option is D.

Explanation:

Metamorphosis can be defined as the change in form, mode of life and behaviour that occurs during embryonic development of an organism. In the metamorphosis of insects, which mostly reproduce sexually, insects can be grouped according to the way the eggs develop into adults. Some show:

--> Complete metamorphosis or

--> Incomplete metamorphosis.

In the life cycle of a butterfly, a COMPLETE metamorphosis occurs. This is because after fertilization, the EGG hatches into LARVA which passes through a PUPAL stage before becoming transformed into an ADULT insect. That is:

Egg --> Larva --> Pupa --> Imago.

When the caterpillar, which is the Larva stage, has reached its full size, it spins a pad of silk on a twig. It moves upward and attached it's clasper to this pad. It spin another silk thread at the thorax. These aids it to assume a slanting position with the head end pointing upwards. The pupa stage called the CHRYSALIS is reached when it tucks it's head under its thorax, arches it's body, shortens and broadens, and moults for the last time. Therefore the correct option is D (pupa).