J:Son Sweden's Caddis Larva is a realistic fly for trout, grayling and rainbow trout fishing.

Larvae live in the bottom of the river and they are important food source for all fish species which eat insects. Best fishing tactic is "high sticking" and traditional "Czech nymphing" with short line and long rod. It is recommended to add some extra weight to leader to get the fly deep enough where the fishes lay.

In the chart below you can see approximate fly and hook sizes: