A blood sucking caterpillar? Should I be worried about the bite?

Hi everyone,

Today, while sitting on a chair in a garden for a while, I realized a green caterpillar-like (4-5cm long, 1-1.5cm diameter) worm was sucking blood off my hand for a while. The picture is here:
http://imgur.com/a/qEWYK

The bite has not left a considerable mark, it was quite visible when there was blood on it, after washing it, the marks seemed like almost invisible pink dots.

What is scary is that I did not find any reference to such an insect anywhere. No one has shared the experience of being bitten by such an insect apparently.

When it was happening, I had no feeling, however, there was a strong smell, something like the smell of those garbage trucks, and after a while I suddenly sensed something on my hand. About the smell my guess is it was generating some sort of chemical which perhaps was to sedate my skin not to feel the bite, something like what a leech does.