This really brings back memories from two years ago. Around the time when I was ten, I planted two milkweed plants along with many other nectar plants expecting for some monarchs to lay their eggs on the milkweed. four years passed and one plant died. No signs of caterpillars were present until January of 2013. Four little ones were hiding on the underside of the leaf. Right next to the plant, I saw an adult monarch, torn to pieces. Due to the near freezing temperatures, I took the orphans in and raised them until adulthood, where I kept them among my orchids and fed them with oranges and sugar water. They stayed in the area for some reason and never left the corner of the living room where I grew my plants even if i placed their food source somewhere else. I still keep their wings in a drawer next to my bed as a memory of those months. Here's two pictures of one of them on my Psychopsis.