I don?t think that they do?at least not often. Trout can?t perceive detail like we can. I heard Gary Borger use the following analogy. A hawks vision is 300x more detailed than a humans, hence its ability to pick mice out of a field. That same ratio is roughly descriptive of trout and humans (that our vision is able to pick out substantially more detail). Trout key in on the silhouette and the color?. Imagine sitting under a fly as it drifts towards you. You actually wouldn?t see the hook if you are under it, unless you are a couple of inches to the left or right. Most trout won?t leave a feeding lane to grab food. I know that?s because it?s a waste of energy, but I also think its because the silhouette (in this case) is pretty far from what an insect would actually look like. There are certainly exceptions to this rule since I?ve seen many trout streak out of their feeding lane to grab food, but I do think that generally the trout looses the tree in the forest (i.e. the hook in the silhouette)