The Caddisflies (Trichoptera) of Drummond Island, Michigan, With an Assessment of Lake Assemblage Biomass

The adult caddisfly assemblages of Drummond Island, a Michigan island in Lake Huron near the Canadian border, were sampled in 2021–2022 from 3 sites on Lake Huron, 8 inland lakes, 2 vernal pools, and 1 stream. Adult caddisflies from each site were sampled in spring, summer, and autumn using ultraviolet blacklight traps. A total of 89 species representing 37 genera and 12 families was collected, including several not seen in Michigan for 50–70 years and the first confirmation of the rare species Beothukus complicatus (Banks) (Phryganeidae) from the state. A non-metric multidimensional scaling ordination determined distinct species assemblages between lakes, vernal pools, and the stream, but no difference between inland lakes and Lake Huron sites. Based on total organic biomass, all 4 habitat types were dominated (60–90%) by shredders, particularly those in the family Phryganeidae. Total species richness was lower on Drummond Island than within other Michigan areas where rigorous recent sampling has occurred, possibly due to it being an isolated island. This study provides some of the first data on the caddisfly assemblages of undisturbed lakes in a Nearctic temperate environment and demonstrates the importance of caddisfly shredders in lake habitats.