Brimstones may be found as adults all over the county in a very wide range of habitats. Because their larval foodplants, alder buckthorn and buckthorn, are sparsely distributed through the landscape, adults undertake significant movements across country to find them and mate. Brimstone eggs and caterpillars may only be found on these two shrubs. Alder buckthorn is scarce but widespread in fen habitat, occurring in the Broads, the Fens, North Norfolk and elsewhere. Buckthorn is more restricted to the Brecks, where it is often common.