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.
The mini-plots experiment was made on the effectiveness of selected chemicals to reduce damage to Chinese cabbage caused by Arion lusitanicus slugs. Two active substances used as spray, seed coating and molluscicides were tested. Effective action in reducing plant damage by slugs showed methiocarb and abamectin used as spray. The damage was reduced also by abamectin used as a seed coating. It was found that the effectiveness of methiocarb and abamectin, applied in the form of spray, was comparable to the efficiency of molluscicide Mesurol Alimax 02 RB (2% methiocarb).