Estimation of slug populations



It is impracticable to count slugs per unit area in the field, but both slugs and their eggs are recovered efficiently by soil washing in the laboratory. A less laborious method is described in which slugs (only) are expelled from turves progressively immersed in cold water. This method, used with samples of twelve 12×12×4 in. units of substratum, gives satisfactory estimates for Agriolimax reticulatus and Arion intermedim at population densities above I per sq.ft.