How does a caterpillar choose a place to pupate?

When monarchs are in their chrysalis, they are vulnerable to predation by wasps and flies. It's important for caterpillars to find a spot that they feel secure from predators, as well as sheltered from wind and rain. Caterpillars do not usually pupate on their host milkweed plants. Instead, they move as far as 10 meters from their initial plant to a tree, another plant, or even the side of a house!