At times I have been confronted with hatches or pre-hatches phases when the fish would eat very tiny things from the surface or right beneath. In these times, even
an 18 size hook would be overdimensioned.
Typical feeders on these tiny insects are grayling and char, and big trout are no exceptions. Especially when a large number of nymphs are drifting in the water column.
Picture: A juvenile stonefly larva plays dangerously close to the jaws of a Hydropsichae