What is this???

The insect is still in a cocoon type home. At first I thought it was comning out of it's cocoon (it's head and a couple of portions of body), but it is actually moving sideways along the railing, leaving a very fine silk trail. The insect is black and orange and sort of looks like a caterpiller but much bigger, with seperated body portions and small clippers for legs.
The cocoon is perfectly made of the silk-like substance (but brown) and has sticks perfectly interwoven, facing vertically down.
The closest thing I have found on web search is a Cicada Killer Wasp.. the colours are identical!
I am really curious to know what this is??