The Large Dark Olive (L.D.O.) is one of the first flies to hatch on the river in spring. Often you can get L.D.O.s hatching on the opening day of the new season if the weather is mild enough. Other times it can be as late as April before they start hatching. Weather conditions will dictate when they start hatching. It is the most important fly for the dry fly angler for the months of March and April and again in September. A must have fly for any dry fly angler in Ireland or the UK.
A great pattern for fishing in the evening time when the trout are feeding on olives or other upwinged flies. In the evening sun all flies have a reddish hue from the weak evening sun and this fly will represent the majority of upwinged duns or spinners.
Originally used to imitate an emerging Stonefly but it will work well for trout on rivers that have never seen a Stonefly.