IF you have found yourself in this situation and you want to raise a Monarch caterpillar indoors, then there are a variety of things you can do. Here is one way to do it.
Get your Fiskar scissors and a container ready. If the container doesn't have holes in the lid, poke a few in the lid (from the INSIDE out!).
With scissors, carefully cut around the egg, leaving just a small amount of the leaf. Place the cut leaf and egg into the container. Watch for changes in the egg (about four days). The egg will change colour...a little dark spot will appear at the top of the egg. This is the caterpillar's head! Once you see this, place a leaf in the container as the caterpillar will soon hatch.