Presently, the DNR states there are 245 species of caddisflies (Trichoptera) identified in 19 families and 72 genera in Wisconsin. They are found in both lentic (lakes & ponds) and lotic (flowing water) aquatic environments. Caddis larvae use silk to spin filter nets to collect food or to help construct shelters. All caddisfly larvae pupate in some sort of enclosed silken cocoon.
Caddisflies hatch throughout the Spring, Summer and Fall season and are a major source of food for trout. They vary in color, and size and emerge at different times of the day and night. Some of the largest caddisflies, such as the Great Brown Sedge (Pycnopsyche) are over an inch long and emerge at night during the Summer. In the Spring on the Northern Wisconsin trout streams it is common to see several different Brachycentrus species emerge, such as the American Grannom (darker olive body with a dark brown wing, size #18) or the Apple Caddis (very light tannish colored wing with an apple green body, size #16).
Hydropsyche and Cheumatopsyche caddis genera (Family: Hydropsychidae) are perhaps the most abundant and widespread Wisconsin caddisflies. They are found all over the state in almost every stream and river, living among the rocks in the riffled waters. Most species make a silken mesh net to capture tiny food particles in the drift. Some of the species are omnivorous and others are herbivores. The ovipositing females swim to the stream bottom rocks to lay their eggs.
The Little Short-Horn Sedge (Glossosoma) comes off around the same time as the Hendrickson hatch (Ephemerella subvaria) and often goes unnoticed by the fly fishermen. They are small, size (#16 - #18) caddis that can get the trout's attention and make fishermen frustrated wondering what the heck the trout are feeding on. Glossosoma larvae make small round huts out of tiny pebbles on the rocks along the stream bed. The larva is whitish-colored. As the larva grows they must abandon their pebble homes and build a new larger one, which makes them vulnerable to the trout while in the drift looking to establish a new home. A size #16, squirrel dubbing body with a silver wire ribbing and a partridge collar makes a deadly soft hackle pattern for the emerging Glossosoma pupae.
See also: Caddisfly Life Cycle for more detailed information.
Below are listed some of the most dominate caddisfly hatches found on northern Wisconsin freestone streams. Many hatch at dusk or after dark during the summer and early Fall, and are missed by fly fishermen.
This is a really cool PBS video showing caddisfly larva making their stone cases.
Below are some caddisfly photos I have taken over the years in northwest Wisconsin.
These large stick case larvas may be Hydatophylax argus, the Giant Cream Pattern-Wing Sedge which emerges during the summer nights. It has a cream-colored body and light-colored wings. There is also another very large caddisfly in the family Limnephilidae genus Pycnopsyche (Great Brown Autumn Sedge), also called the October Caddis, which emerges in September or October in Wisconsin. The adult caddis is about 20mm long and has a burnt orange colored body and a brownish mottled wing.
Notice the green body of this size #16 tannish wing caddisfly. These caddisflies emerge sporadically throughout the days in May in many northern Wisconsin trout streams. The body is more of a size #18 and the wing is a size #16, which is typical of caddisflies. An X-Caddis pattern or CDC & Elk works well for this stage. See the photo below.