In the years 2002–2003, observations were carried out in Podkarpackie area on the intensity of occurrence of Arion lusitanicus and damage degree caused to cultivated and uncultivated plants. It was found that A. lusitanicus feeds on awide range of plants, both on crops and commonly occurring weeds. Almost all vegetable species were damaged severely and some plant species from the other groups as well. Indications of the slug feeding were found on 103 plant species