After approx 10-12 days one of them started changing colour. It turned green in about 10-12 hours. Morning it was normal, black with white stripes, and evening it was completely transformed into green colour.
You can see both of them in two avatars in below picture, one of them is transformed into green caterpillar, while other is still to be transformed, though it has started showing green spots, starting to turn green.
I must say once it is transformed to green one, it looks very cute. Its been growing fast and eating much too. We usually put fresh curry leaves twice a day, and open the jar for fresh air. They are quite lousy and lazy, mostly laying around lazily when they are not eating curry leaves. The speed at which they eat those leaves is mind boggling. You can watch them eating leaves -
The typical life cycle of these caterpillars is about 4 -5 weeks. We found them about 6-7 times so far and have followed their life cycle closely from egg to a butterfly. Egg is very tiny one and you have to have keen observation skill to notice them. When the caterpillar comes out of an egg, firth thing it does is - eat the remnants of that egg. There are two reason for their doing so
a) They are very hungry when they come out and b) Not to leave any traces for a predator to know about their existence. How carefully nature has designed such things or probably the way every creature has evolved to survive.
Typically these caterpillars are just black and ugly for about 1-2 weeks and start turning green. At the time of turning green, they shed their skin and eat it immediately so that there are no traces. The green caterpillars get absolutely camouflaged in the tree leaves, and it is hard to spot them easily. Another adoption for survival.
Once they turn green, it takes another 1 - 1 1/2 week for them to go into a cocoon. The way they build cocoon is another amazing activity to observe. They attach lower part of their body to any available surface (it could be anything from a jar, a wall, a shady corner in house, or below a chair). Usually they prefer a place where they wont be noticed easily, again to stay safe from predators. And they turn upper part of their body outside making it look like a 'J'. They bind upper part of their body with two thin strings on each side. It takes good amount of it to fine tune those two strings and it is fun to watch them doing so. They stay in cocoon for another week to 10 days. I am told that they may remain in the cocoon for up to a year, if they sense any danger in coming out of it. Usually they come out of cocoon early morning and you better have them covered with a net or have them in a jar otherwise you might miss the butterfly. You can predict when the butterfly would come out by observing the cocoon every day. One day before coming out, the inner side of the cocoon turns black. A newly born butterfly takes about an hour to open its wings completely and be able to fly on its own. I used to wonder at how amazingly most the creatures (bugs, insects, birds, animals) become independent in short time after they are born while human child is dependent on its parents for so long time. But on a second thought I think its in proportion with the overall lifespan of the creature. I would love to find out more about this proportion for different bugs, animals, birds.
Surprise surprise!! The female butterflies are more beautiful than male ones. They have trendy and curvy wings and more attractive colours on their wings. There nothing like the joy of watching them fly freely around a tree full of bloom.
If you are planning to observe this life cycle, I would advice you to make sure that a cocoon is placed in a large container or net where it get enough space to open its wings fully. Its important that they open their wings fully in first hour, otherwise they might not open them properly later and you might repent hurting an innocent and beautiful life. Also please make sure that you set them free as soon as possible, as nobody loves living in captivation. We do all these activities just to study them, but follow many guidelines not to hurt them.