We currently have two monarch caterpillars in full chrysalis construction mode sitting on a milkweed plant in our kitchen. We put netting over the plant to protect them from the cats. The caterpillars are more fascinating than I thought they would be. They basically ate for several days in a row - and that's all they did, all day long, and all night long, too. It was astonishing to see how much they ate. Then they both found a spot on the plan and compacted themselves (one of them was about 2 inches long, the other about 3 inches long, and they both compacted themselves to about 1 inch), and then curled into a "J" shape, and they seem to be secreting a substance from one end of their bodies.
When they emerge from their chrysali, we will bring them to Magic Wings butterfly conservatory in So. Deerfield, MA.