Terrestrial slugs of the genus Arion are native to Europe, where they represent an important agricultural pest. This study determined the effectiveness of electrified fencing on barrier crossing by slugs. The fences were placed in glass insectariums. DC (direct current) voltages (2, 4, 6, 8 and 10 V) applied across the fence were tested together with limiting electric current values (0.1, 0.01 and 0.001 mA). Four categories of behavior were identified for slugs in the presence of an electrified fence: the animals (1) were stationary, (2) were moving but avoided the electrodes, (3) touched the electrodes and/or attempted unsuccessfully to cross the electrified fence and (4) succeeded in crossing the electrified fence. The effect of the applied voltages and the limiting current values on slug movement was highly significant. Forty-one percent of slugs crossed the fence at the lowest applied voltage, whereas only 1% of slugs succeeded in crossing at the highest voltage. The lowest limiting current values resulted in the most frequent fence crossings. For larger voltages and limiting currents, the frequency of slug crossings was effectively zero at fence regions positioned on the glass walls of the insectariums. In conclusion, this method of slug prevention may be highly effective, environmentally friendly and may result in deterrence, not death, of terrestrial slugs, a ubiquitous pest responsible for significant economic damage in agriculture.