Green caterpillar, what is it?

Question

It's about 2 cm long, has no hair, 3 pairs of legs in front and 2 or 3 behind (can't qite tell), segmented body (but I suppose all catterpillars have that), light green colour and the head is a lighter shade, yellowish.

What is it?

I found it on my curtain. I put it in a jar and placed some leafes next to it and now I'm waiting to see what happens :). Does it need anything more than leaves? Can it actually grow into a nympph and then into a butterfly?

Answer 1

oops, my bad... that first link is the Hummingbird sphinx (hemaris thysbe)

the site with all the families is: http://www.npwrc.usgs.gov/resource/insects/cateast/silkworm.htm

Answer 2

It is a caterpillar, sounds like perhaps a small hummingbird sphynx :http://www.silkmoths.bizland.com/hthysbe.htm

if thats not it, that site has a very good list, with pictures of all sorts of families of caterpillars