How can you tell when a Monarch caterpillar has just slipped out of it's skin?
The giveaway, of course, is the empty skin. There are other signs, however.
Notice how it's head is very pale and it's feet almost look clear? They will both colour up very quickly, but being so pale is also a sign that the caterpillar has just shed its skin.
I have noticed that, just before shedding a skin, a monarch caterpillar will stay very still in the same place on the leaf for about 2 days without eating. Once it has shed it's skin, it continues to remain still for quite a long time and then it turns around and eats the discarded skin.
During its growing time as a caterpillar, the monarch caterpillar sheds its skin 5 times.
The empty skin is called exuvia.
During the shedding process it wriggles the skin slowly down its body, starting from the head. As the moving skin reaches the legs it pulls them out of the unwanted skin, two at a time. Eventually the skin is eased right off the body but, guess what?
The 'face' will still be on the caterpillar. Now it rids itself of the old face to reveal a new face.
If you happen to see a tiny bit of shiny black circle with holes in it, near to a caterpillar that has just shed its skin, that's the old face.
Today, small caterpillar is looking decidedly larger and is munching happily on a swan plant leaf.
Oh - and the other good news is that one of the other eggs hatched and so now we have 3 caterpillars on the leaves. Meanwhile, tiny caterpillar who hatched 3 days ago, is coming along nicely and is now 5mm long. Perhaps I should now call it small2?