What is this?

The other day when I was at our workingspace I felt something itching on my shoulder. When I looked I saw this tiny (1.5cm= 5/8'') neon green worm (Catepillar?). It was moving like crazy and super fast. Luckly camera was nearby, I took it on my finger to take a proper picture. In no time it moved from my pointing finger to my pinky, handpalm and up again towards my shoulder.



His/ her movements where hilarious.

Never have seen this kind of fun creature before, wonder how it ended up in our workspace.
After the pictures I've set her free between some lovely leaves...