Shortjawed kokopu from diverse localities feed extensively on several species of cased caddisflies from the stream benthos and on diverse terrestrial invertebrates from the surface. Small caddisflies often dominate the diet numerically and are selected for, whereas other often abundant benthic insects, such as Chironomidae and the mayflyDeleatidium, are avoided. We hypothesise that this selectivity indicates that caddisflies are taken by grazing the benthos rather than from the invertebrate drift. Gravimetrically, large terrestrial invertebrates such as beetles, ants, cicadas, and spiders are more prominent in shortjawed kokopu diet. Stable carbon isotope analysis shows that in Black Creek, a tributary of the Ohinetamatea River, South Westland, a high proportion of the material assimilated from the diet is of terrestrial origin.