Here is what I've notice occuring with this species and others, before pupation: 1. 5th instar color fades 2. They lose their ability to grip branches and twigs 3. They begin to wonder 4. They become inactive and their bodies become rigid, alost muscular (they wiggle when disturbed) 5. You may find some debris which may look like black specs, which I believe is the remaining food in their guts which they have regurgitated before pupation (this stuff looks nothing like frass!)

(Editor's note: Image dates are from June - July 2006. Raised in Ottawa, Ontario but this information removed from date field as these were captive-raised, not local specimens)