Caddisfly (Trichoptera) Assemblages from the Southern Laurentian Highlands, Québec (Canada)

The caddisflies (Trichoptera) represent an important taxon for the natural functioning of aquatic ecosystems and as biological monitoring organisms; however, basic information on their assemblages is still lacking in Canada. In this study, adult caddisflies from 30 lakes and streams in the southern Laurentian Highlands of Québec were sampled during 2023–2025. A total of 186 caddisfly species were determined, including 22 species not previously reported from Québec and eight not previously reported from anywhere in Canada. Two species of Cernotina also represented the first collection of that genus within the province. Using Indicator Species Analysis, six species indicated small rivers, 14 indicated large rivers, and six indicated lakes. Based on summer sampling, the assemblages of small rivers and lakes were dominated by shredders, whereas larger rivers were dominated by filtering collectors, gathering collectors, and predators. This study provides data on the functional feeding group assemblages of generally undisturbed lake and stream habitats, and demonstrates the importance of continued sampling throughout Québec.