Tandonia kusceri (H. Wagner) is a terrestrial slug native to the Balkan Peninsula (S. Serbia, N. Macedonia, Bulgaria and Dobrudja region of Romania) and the European part of Turkey. In Serbia, it was known mostly from the southern regions. The northernmost locality (Palić settlement, near Subotica) reported here suggests that the slug’s distribution is nearly continuous from its native range until Slovakia. The new record was first recognised from the pictures posted on a Facebook group for insect identification in 2021. The identification was subsequently confirmed by anatomical examination. This further emphasises the importance of social media in monitoring the spread of invasive invertebrates.