These are my amazing monarch caterpillars. They were used  to cause foliar  damage to Milkweed plants  in my experiment that summer.  I was examining tolerance and resistance in milkweed in response to herbivory.
My plot for this experiment.  The flags mark the plants and the white things are the cloth bags on the plants.  These keep the monarch larvea in and the other herbivores and predators out.  A beautiful spot to do ecology experiments.
Joker's Hill is a beautiful place to work in the summer.  Milkweed grows abundantly and many of the specialist herbivores for the plant occur naturally in this area.  Its proximity to Toronto (45 min drive) also makes it an ideal research area.
Joker's Hill Research