Last August I had four monarch butterfly larvae chewing up milkweed leaves on my kitchen windowsill as fast as I could provide them. The caterpillars were borrowed from the elementary school habitat as eggs to show to children in a workshop in a few weeks. Well, they hatched before the workshop so I showed the caterpillars instead. (So small upon hatching that I didn’t notice for a few days!) There were five to begin with, but one morning I came down and saw a spider with one of the caterpillars (half inch long at that point) in its grip. Needless to say, that spider had to move outside and the rest of the caterpillars moved into a large pretzel container. Here I thought I was protecting these babies by keeping them indoors! The remaining four went home to the school habitat after the workshop.
Journey North, a website from Annenberg Media that engages students in a global study of wildlife migration and seasonal change, has a Monarch butterfly migration page for information and to report sightings.