Some yarns can just be the ticket. Like this green yellow olive something I got from Staffan Lindström. It is perfect for extended bodies like the one on this sedge emerger. (Tied on a CZF hook size 20).
However, these tiny amounts - a few yards are good for a lifetime - are difficult to store. I found this to be a neat trick... just wind the yarn around a clothes peg and hey presto, you save hours untangling!