If this is what I think it is, a blowfly, it may be pretty but it's a nasty beast. The female blowflies (as this one seems to be: notice her big widely separated eyes) lays its eggs on the damp and smelly parts of animals like sheep. Soon the eggs hatch out and the larvae have insatiable appetites for raw meat, thus doing in said poor sheep.

Next time I see one, I'm reaching for my fly-swatter.