EN
This paper presents preliminary results of observations of circadian activities of one of the tested slug species – Arion lusitanicus. The study was conducted in laboratory conditions at two different temperatures 10 and 16ºC. The results showed that slugs were much more active at night than during the day. Most of the time during the day they spent in shelter, but little time devoted to nutrition. Arion lusitanicus slugs activity was significantly lower at 10 than at 16°C.