Northern Caddisflies
This common name refers to only one family.
These are very rarely called Northern Caddisflies.
This huge family appropriately contains huge caddisflies. Many of its genera are important, but the western genus
Dicosmoecus (the Giant Orange Sedge or October Caddis) is especially important as a big-trout hatch.
Limnephilidae contains so many species that it is difficult to generalize about them all. LaFontaine commented on the task in
Caddisflies:
The fact that fly fishermen need broad principles of biology, not a collection of exceptions, makes it difficult to handle this family.
I recommend learning which genera or species are prevalent in your area and studying them specifically.