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There have been widespread changes in land use in the uplands of the UK but the implications for dispersal of adult stages of aquatic invertebrates are poorly known. We estimated the lateral dispersal of adult aquatic insects (Plecoptera, Trichoptera, Ephemeroptera) in seven small, upland streams draining catchments under three categories of land use (coniferous plantation forest, cleared forest, moorland).

Malaise traps were set out in transects perpendicular to each stream. More than 29 000 adult insects were taken, distributed among 15 species of stoneflies, 40 species of caddisflies and eight taxa of mayflies. Overall species diversity and equitability were highest in the moorland catchments, and few species were numerous in all catchments.

Nearly all the mayflies were taken in the moorland catchments, where caddisflies were also most abundant. Fewest stoneflies were taken in the forested …