Why are caterpillars climbing walls?

If you see lots of caterpillars climbing walls at the same time it's usually because they are looking for a place to hang and pupate (sp) They find a spot and hang upside down in a J shape. After a few days they become a chrysallis and within about a week to 10 days they are butterflies. If you can, put some caterpillars in a butterfly house or bug catcher and watch them. Just remember to keep them out of direct sunlight and make sure you let them go as soon as they turn into butterflies.