Green,blue, and black dragonscaleFollow

Did you try the search box on the left here? It will tell you which mobs drop the items and the drop percentage. Unfortunately, it doesn't tell you whether you need to skin the mob to get the item to drop - do you actually have to skin the dragons to get these or are they just drops?

I'm not a skinner but here is the list of mobs I know (not comprehensive by any means)

Green: Dragonkin in The Sunken Temple Instance

Black: Dragonkin in the Burning Steppes
Dragonkin in UBRS

Blue: Dragonkin in Winterspring southwest of Everlook
Dragonkin in Azhara by the lake to the south
Dragonkin in the far northeast of the Hinterlands

Red: Dragonkin in the East of the Wetlands
Dragonkin in UBRS

The Dragonkin range between 55 and 62 elites both casters and melee. The whelps of the same colour will normally be around their respective dragonkin areas but are very much less likely to drop scale when skinned.