Nearly 150,000 caddisfly specimens representing 238 species were analyzed from 166 5–15m wide streams within Michigan and Minnesota to deter- mine the characteristic indicator species of 5 previously-established regions of caddisfly biological diversity. Based on a combination of relative frequency and abundance, 35 of these species indicated a particular region or regions. Indicator species in forested regions constituted a balance of trophic functional groups, whereas indicator species from agricultural regions were dominated by filtering collectors. While it was difficult to determine if species were indicating natural habitat type or differences in anthropogenic disturbance, establishing indicator species now will render potential future changes to the fauna easier to evaluate
