EN
This paper lists alien invasive species of slugs occurring on crops grown in the ground and under covers, as well as in adjacent habitats. It gives a description of their origin, distribution within Poland, frequency of occurrence in different habitats, and an evaluation of the danger to cultivated plants posed by particular slug species. Based on reports in the literature and the results of original research, basic data is presented concerning the biology and harmfulness of these slugs on crops. The potential risk of the spreading of invasive slug species is evaluated, as well as their adverse impact on crop plants. It has been concluded that a major risk to the biodiversity of agrocenoses and to cultivated plants is currently posed by the slugs Arion lusitanicus, A. rufus and A. distinctus. These slugs are spreading rapidly within Poland, often occur in large numbers, and do significant damage to various species of plant.