From the egg seen in Part 1-The Monarch Egg you’ll see at the last change before it hatches you’ll see a tiny dark spot that is its head.
This one has just hatched. It has no color on its body yet. Note the stripes on the shell of the egg.
Above you’ll see how tiny they are. They are even a bit smaller than this as they leave their egg. This one has already eaten a portion of the leaf and has gotten some color to his body.
Above is several hours after hatching and it is taking on the look of the larger caterpillars with the yellow and black stripes. How cute they are!
Above you’ll see they have gotten quite a bit bigger. I put them in an old bread warmer I got with a toaster oven that I never used. As long as you give them fresh milkweed they will pretty much stay in the area you put them. If they can’t find food, they will try to escape. You need to clean out the leaves and debris a few times a day and keep them at normal temperature. Make sure no sun gets to them if you have them in a container that would heat up. Make sure they have ventilation. Be careful when handling the leaves so you don’t accidentally kill one.
Below are some videos I took a couple of years ago. That was before the quality was upgraded on the video websites but you can still see the caterpillars pretty good.